diff --git a/src/test/java/org/codehaus/plexus/interpolation/EnvarBasedValueSourceTest.java b/src/test/java/org/codehaus/plexus/interpolation/EnvarBasedValueSourceTest.java
index 8a3c76c..37af0a4 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/EnvarBasedValueSourceTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/EnvarBasedValueSourceTest.java
@@ -1,24 +1,6 @@
 package org.codehaus.plexus.interpolation;
 
-/*
- * Copyright 2007 The Codehaus Foundation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import java.io.IOException;
 import java.util.HashMap;
-import java.util.Map;
 
 import org.codehaus.plexus.interpolation.os.OperatingSystemUtils;
 import org.junit.jupiter.api.BeforeEach;
@@ -28,21 +10,19 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
-public class EnvarBasedValueSourceTest {
+class EnvarBasedValueSourceTest {
 
     @BeforeEach
-    public void setUp() {
+    void setUp() {
         EnvarBasedValueSource.resetStatics();
     }
 
     @Test
-    void testNoArgConstructorIsCaseSensitive() throws IOException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("aVariable", "variable");
-                return map;
-            }
+    void noArgConstructorIsCaseSensitive() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("aVariable", "variable");
+            return map;
         });
 
         EnvarBasedValueSource source = new EnvarBasedValueSource();
@@ -54,13 +34,11 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    void testCaseInsensitive() throws IOException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("aVariable", "variable");
-                return map;
-            }
+    void caseInsensitive() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("aVariable", "variable");
+            return map;
         });
 
         EnvarBasedValueSource source = new EnvarBasedValueSource(false);
@@ -72,7 +50,7 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    void testGetRealEnvironmentVariable() throws IOException {
+    void getRealEnvironmentVariable() throws Exception {
         OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.DefaultEnvVarSource());
 
         EnvarBasedValueSource source = new EnvarBasedValueSource();
diff --git a/src/test/java/org/codehaus/plexus/interpolation/FeedbackingValueSourceTest.java b/src/test/java/org/codehaus/plexus/interpolation/FeedbackingValueSourceTest.java
index f6304ad..909e4fa 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/FeedbackingValueSourceTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/FeedbackingValueSourceTest.java
@@ -23,10 +23,10 @@
 import static org.junit.jupiter.api.Assertions.assertNull;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-public class FeedbackingValueSourceTest {
+class FeedbackingValueSourceTest {
 
     @Test
-    public void testStandalone() {
+    void standalone() {
         ValueSource valueSource = new FeedbackingValueSource();
         assertNull(valueSource.getValue("test"));
         assertEquals(1, valueSource.getFeedback().size());
@@ -34,7 +34,7 @@ public void testStandalone() {
     }
 
     @Test
-    public void testAfterResolvedExpression() throws InterpolationException {
+    void afterResolvedExpression() throws Exception {
         StringSearchInterpolator interpolator = new StringSearchInterpolator();
         interpolator.addValueSource(new MapBasedValueSource(singletonMap("key", "val")));
         interpolator.addValueSource(new FeedbackingValueSource());
@@ -43,7 +43,7 @@ public void testAfterResolvedExpression() throws InterpolationException {
     }
 
     @Test
-    public void testBeforeResolvedExpression() throws InterpolationException {
+    void beforeResolvedExpression() throws Exception {
         StringSearchInterpolator interpolator = new StringSearchInterpolator();
         interpolator.addValueSource(new FeedbackingValueSource("Resolving ${expression}"));
         interpolator.addValueSource(new MapBasedValueSource(singletonMap("key", "val")));
@@ -53,7 +53,7 @@ public void testBeforeResolvedExpression() throws InterpolationException {
     }
 
     @Test
-    public void testAfterNotResolvedExpression() throws InterpolationException {
+    void afterNotResolvedExpression() throws Exception {
         StringSearchInterpolator interpolator = new StringSearchInterpolator();
         interpolator.addValueSource(new MapBasedValueSource(singletonMap("key", "val")));
         interpolator.addValueSource(new FeedbackingValueSource());
diff --git a/src/test/java/org/codehaus/plexus/interpolation/InterpolatorFilterReaderTest.java b/src/test/java/org/codehaus/plexus/interpolation/InterpolatorFilterReaderTest.java
index 0be913d..4f3a4d0 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/InterpolatorFilterReaderTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/InterpolatorFilterReaderTest.java
@@ -41,14 +41,14 @@
  * @author cstamas
  *
  */
-public class InterpolatorFilterReaderTest {
+class InterpolatorFilterReaderTest {
     /*
      * Added and commented by jdcasey@03-Feb-2005 because it is a bug in the InterpolationFilterReader.
      * kenneyw@15-04-2005 fixed the bug.
      */
     @Test
-    public void testShouldNotInterpolateExpressionAtEndOfDataWithInvalidEndToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateExpressionAtEndOfDataWithInvalidEndToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "TestValue");
 
         String testStr = "This is a ${test";
@@ -60,8 +60,8 @@ public void testShouldNotInterpolateExpressionAtEndOfDataWithInvalidEndToken() t
      * kenneyw@14-04-2005 Added test to check above fix.
      */
     @Test
-    public void testShouldNotInterpolateExpressionWithMissingEndToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateExpressionWithMissingEndToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "TestValue");
 
         String testStr = "This is a ${test, really";
@@ -70,8 +70,8 @@ public void testShouldNotInterpolateExpressionWithMissingEndToken() throws Excep
     }
 
     @Test
-    public void testShouldNotInterpolateWithMalformedStartToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateWithMalformedStartToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "testValue");
 
         String foo = "This is a $!test} again";
@@ -80,8 +80,8 @@ public void testShouldNotInterpolateWithMalformedStartToken() throws Exception {
     }
 
     @Test
-    public void testShouldNotInterpolateWithMalformedEndToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateWithMalformedEndToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "testValue");
 
         String foo = "This is a ${test!} again";
@@ -90,8 +90,8 @@ public void testShouldNotInterpolateWithMalformedEndToken() throws Exception {
     }
 
     @Test
-    public void testDefaultInterpolationWithNonInterpolatedValueAtEnd() throws Exception {
-        Map m = new HashMap();
+    void defaultInterpolationWithNonInterpolatedValueAtEnd() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -101,8 +101,8 @@ public void testDefaultInterpolationWithNonInterpolatedValueAtEnd() throws Excep
     }
 
     @Test
-    public void testDefaultInterpolationWithInterpolatedValueAtEnd() throws Exception {
-        Map m = new HashMap();
+    void defaultInterpolationWithInterpolatedValueAtEnd() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -112,8 +112,8 @@ public void testDefaultInterpolationWithInterpolatedValueAtEnd() throws Exceptio
     }
 
     @Test
-    public void testInterpolationWithInterpolatedValueAtEndWithCustomToken() throws Exception {
-        Map m = new HashMap();
+    void interpolationWithInterpolatedValueAtEndWithCustomToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -123,8 +123,8 @@ public void testInterpolationWithInterpolatedValueAtEndWithCustomToken() throws
     }
 
     @Test
-    public void testInterpolationWithInterpolatedValueAtEndWithCustomTokenAndCustomString() throws Exception {
-        Map m = new HashMap();
+    void interpolationWithInterpolatedValueAtEndWithCustomTokenAndCustomString() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -134,8 +134,8 @@ public void testInterpolationWithInterpolatedValueAtEndWithCustomTokenAndCustomS
     }
 
     @Test
-    public void testEscape() throws Exception {
-        Map m = new HashMap();
+    void escape() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -145,8 +145,8 @@ public void testEscape() throws Exception {
     }
 
     @Test
-    public void testEscapeAtStart() throws Exception {
-        Map m = new HashMap();
+    void escapeAtStart() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -156,8 +156,8 @@ public void testEscapeAtStart() throws Exception {
     }
 
     @Test
-    public void testEscapeOnlyAtStart() throws Exception {
-        Map m = new HashMap();
+    void escapeOnlyAtStart() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -168,8 +168,8 @@ public void testEscapeOnlyAtStart() throws Exception {
     }
 
     @Test
-    public void testEscapeOnlyAtStartDefaultToken() throws Exception {
-        Map m = new HashMap();
+    void escapeOnlyAtStartDefaultToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -180,15 +180,15 @@ public void testEscapeOnlyAtStartDefaultToken() throws Exception {
     }
 
     @Test
-    public void testShouldDetectRecursiveExpressionPassingThroughTwoPrefixes() throws Exception {
-        List prefixes = new ArrayList();
+    void shouldDetectRecursiveExpressionPassingThroughTwoPrefixes() throws Exception {
+        List<String> prefixes = new ArrayList<>();
 
         prefixes.add("prefix1");
         prefixes.add("prefix2");
 
         RecursionInterceptor ri = new PrefixAwareRecursionInterceptor(prefixes, false);
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("name", "${prefix2.name}");
 
         String input = "${prefix1.name}";
@@ -211,14 +211,14 @@ public void testShouldDetectRecursiveExpressionPassingThroughTwoPrefixes() throw
     }
 
     @Test
-    public void testShouldDetectRecursiveExpressionWithPrefixAndWithout() throws Exception {
-        List prefixes = new ArrayList();
+    void shouldDetectRecursiveExpressionWithPrefixAndWithout() throws Exception {
+        List<String> prefixes = new ArrayList<>();
 
         prefixes.add("prefix1");
 
         RecursionInterceptor ri = new PrefixAwareRecursionInterceptor(prefixes, false);
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("name", "${prefix1.name}");
 
         String input = "${name}";
@@ -244,11 +244,11 @@ public void testShouldDetectRecursiveExpressionWithPrefixAndWithout() throws Exc
     //
     // ----------------------------------------------------------------------
 
-    private String interpolate(String input, Map context) throws Exception {
+    private String interpolate(String input, Map<String, String> context) throws Exception {
         return interpolate(input, context, null);
     }
 
-    private String interpolate(String input, Map context, String escapeStr) throws Exception {
+    private String interpolate(String input, Map<String, String> context, String escapeStr) throws Exception {
         Interpolator interpolator = new StringSearchInterpolator();
 
         interpolator.addValueSource(new MapBasedValueSource(context));
@@ -268,7 +268,8 @@ private String interpolate(String input, Map context, String escapeStr) throws E
         return buf.toString();
     }
 
-    private String interpolate(String input, Map context, String beginToken, String endToken) throws Exception {
+    private String interpolate(String input, Map<String, String> context, String beginToken, String endToken)
+            throws Exception {
         StringSearchInterpolator interpolator = new StringSearchInterpolator(beginToken, endToken);
 
         interpolator.addValueSource(new MapBasedValueSource(context));
diff --git a/src/test/java/org/codehaus/plexus/interpolation/PrefixAwareRecursionInterceptorTest.java b/src/test/java/org/codehaus/plexus/interpolation/PrefixAwareRecursionInterceptorTest.java
index d1f250a..e26d427 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/PrefixAwareRecursionInterceptorTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/PrefixAwareRecursionInterceptorTest.java
@@ -25,10 +25,10 @@
 import static org.junit.jupiter.api.Assertions.assertFalse;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-public class PrefixAwareRecursionInterceptorTest {
+class PrefixAwareRecursionInterceptorTest {
 
     @Test
-    public void testFindExpression() {
+    void findExpression() {
         PrefixAwareRecursionInterceptor receptor =
                 new PrefixAwareRecursionInterceptor(Collections.singleton("prefix."));
 
@@ -45,9 +45,9 @@ public void testFindExpression() {
     }
 
     @Test
-    public void testFindExpressionWithDifferentPrefix() {
+    void findExpressionWithDifferentPrefix() {
         PrefixAwareRecursionInterceptor receptor =
-                new PrefixAwareRecursionInterceptor(Arrays.asList(new String[] {"prefix.", "other."}));
+                new PrefixAwareRecursionInterceptor(Arrays.asList("prefix.", "other."));
 
         String expr = "prefix.first";
 
@@ -61,9 +61,9 @@ public void testFindExpressionWithDifferentPrefix() {
     }
 
     @Test
-    public void testFindExpressionWithoutPrefix() {
+    void findExpressionWithoutPrefix() {
         PrefixAwareRecursionInterceptor receptor =
-                new PrefixAwareRecursionInterceptor(Arrays.asList(new String[] {"prefix.", "other."}));
+                new PrefixAwareRecursionInterceptor(Arrays.asList("prefix.", "other."));
 
         String prefixedExpr = "prefix.first";
         String expr = "first";
diff --git a/src/test/java/org/codehaus/plexus/interpolation/PrefixedObjectValueSourceTest.java b/src/test/java/org/codehaus/plexus/interpolation/PrefixedObjectValueSourceTest.java
index 996d090..eafcebf 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/PrefixedObjectValueSourceTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/PrefixedObjectValueSourceTest.java
@@ -23,13 +23,13 @@
 
 import static org.junit.jupiter.api.Assertions.assertNull;
 
-public class PrefixedObjectValueSourceTest {
+class PrefixedObjectValueSourceTest {
 
     @Test
-    public void testEmptyExpressionResultsInNullReturn_NoPrefixUsed() {
+    void emptyExpressionResultsInNullReturnNoPrefixUsed() {
         String target = "Target object";
 
-        List prefixes = new ArrayList();
+        List<String> prefixes = new ArrayList<>();
         prefixes.add("target");
         prefixes.add("object");
 
@@ -40,10 +40,10 @@ public void testEmptyExpressionResultsInNullReturn_NoPrefixUsed() {
     }
 
     @Test
-    public void testEmptyExpressionResultsInNullReturn_PrefixUsedWithDot() {
+    void emptyExpressionResultsInNullReturnPrefixUsedWithDot() {
         String target = "Target object";
 
-        List prefixes = new ArrayList();
+        List<String> prefixes = new ArrayList<>();
         prefixes.add("target");
         prefixes.add("object");
 
@@ -54,10 +54,10 @@ public void testEmptyExpressionResultsInNullReturn_PrefixUsedWithDot() {
     }
 
     @Test
-    public void testEmptyExpressionResultsInNullReturn_PrefixUsedWithoutDot() {
+    void emptyExpressionResultsInNullReturnPrefixUsedWithoutDot() {
         String target = "Target object";
 
-        List prefixes = new ArrayList();
+        List<String> prefixes = new ArrayList<>();
         prefixes.add("target");
         prefixes.add("object");
 
diff --git a/src/test/java/org/codehaus/plexus/interpolation/PrefixedValueSourceWrapperTest.java b/src/test/java/org/codehaus/plexus/interpolation/PrefixedValueSourceWrapperTest.java
index 1e65b9b..cc3439f 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/PrefixedValueSourceWrapperTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/PrefixedValueSourceWrapperTest.java
@@ -23,10 +23,10 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
-public class PrefixedValueSourceWrapperTest {
+class PrefixedValueSourceWrapperTest {
 
     @Test
-    public void testShouldReturnValueForPropertyVSWRappedWithSinglePrefix() {
+    void shouldReturnValueForPropertyVSWRappedWithSinglePrefix() {
         String prefix = "prefix.";
         String key = "key";
         String value = "value";
@@ -41,7 +41,7 @@ public void testShouldReturnValueForPropertyVSWRappedWithSinglePrefix() {
     }
 
     @Test
-    public void testShouldReturnNullForIncorrectPrefixUsingPropertyVSWRappedWithSinglePrefix() {
+    void shouldReturnNullForIncorrectPrefixUsingPropertyVSWRappedWithSinglePrefix() {
         String prefix = "prefix.";
         String otherPrefix = "other.";
         String key = "key";
@@ -57,7 +57,7 @@ public void testShouldReturnNullForIncorrectPrefixUsingPropertyVSWRappedWithSing
     }
 
     @Test
-    public void testShouldNullForMissingValueInPropertyVSWRappedWithSinglePrefix() {
+    void shouldNullForMissingValueInPropertyVSWRappedWithSinglePrefix() {
         String prefix = "prefix.";
         String key = "key";
 
diff --git a/src/test/java/org/codehaus/plexus/interpolation/PropertiesBasedValueSourceTest.java b/src/test/java/org/codehaus/plexus/interpolation/PropertiesBasedValueSourceTest.java
index 6fe10b8..b571ec5 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/PropertiesBasedValueSourceTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/PropertiesBasedValueSourceTest.java
@@ -23,10 +23,10 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
-public class PropertiesBasedValueSourceTest {
+class PropertiesBasedValueSourceTest {
 
     @Test
-    public void testPropertyShouldReturnValueFromProperties() {
+    void propertyShouldReturnValueFromProperties() {
         Properties props = new Properties();
 
         String key = "key";
@@ -40,7 +40,7 @@ public void testPropertyShouldReturnValueFromProperties() {
     }
 
     @Test
-    public void testPropertyShouldReturnNullWhenPropertyMissing() {
+    void propertyShouldReturnNullWhenPropertyMissing() {
         Properties props = new Properties();
 
         String key = "key";
diff --git a/src/test/java/org/codehaus/plexus/interpolation/RegexBasedInterpolatorTest.java b/src/test/java/org/codehaus/plexus/interpolation/RegexBasedInterpolatorTest.java
index f2debe4..d701387 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/RegexBasedInterpolatorTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/RegexBasedInterpolatorTest.java
@@ -1,22 +1,5 @@
 package org.codehaus.plexus.interpolation;
 
-/*
- * Copyright 2001-2008 Codehaus Foundation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.Properties;
@@ -31,7 +14,7 @@
 public class RegexBasedInterpolatorTest {
 
     @BeforeEach
-    public void setUp() {
+    void setUp() {
         EnvarBasedValueSource.resetStatics();
     }
 
@@ -40,7 +23,7 @@ public String getVar() {
     }
 
     @Test
-    public void testShouldFailOnExpressionCycle() {
+    void shouldFailOnExpressionCycle() {
         Properties props = new Properties();
         props.setProperty("key1", "${key2}");
         props.setProperty("key2", "${key1}");
@@ -58,7 +41,7 @@ public void testShouldFailOnExpressionCycle() {
     }
 
     @Test
-    public void testShouldResolveByMy_getVar_Method() throws InterpolationException {
+    void shouldResolveByMyGetVarMethod() throws Exception {
         RegexBasedInterpolator rbi = new RegexBasedInterpolator();
         rbi.addValueSource(new ObjectBasedValueSource(this));
         String result = rbi.interpolate("this is a ${this.var}", "this");
@@ -67,10 +50,10 @@ public void testShouldResolveByMy_getVar_Method() throws InterpolationException
     }
 
     @Test
-    public void testShouldResolveByContextValue() throws InterpolationException {
+    void shouldResolveByContextValue() throws Exception {
         RegexBasedInterpolator rbi = new RegexBasedInterpolator();
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap();
         context.put("var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
@@ -81,7 +64,7 @@ public void testShouldResolveByContextValue() throws InterpolationException {
     }
 
     @Test
-    public void testDelimitersPassedToValueSource() throws InterpolationException {
+    void delimitersPassedToValueSource() throws Exception {
         RegexBasedInterpolator interpolator = new RegexBasedInterpolator();
         interpolator.addValueSource(new AbstractValueSource(false) {
 
@@ -103,13 +86,11 @@ public Object getValue(String expression) {
     }
 
     @Test
-    public void testShouldResolveByEnvar() throws IOException, InterpolationException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("SOME_ENV", "variable");
-                return map;
-            }
+    void shouldResolveByEnvar() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("SOME_ENV", "variable");
+            return map;
         });
 
         RegexBasedInterpolator rbi = new RegexBasedInterpolator();
@@ -122,10 +103,10 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    public void testUseAlternateRegex() throws Exception {
+    void useAlternateRegex() throws Exception {
         RegexBasedInterpolator rbi = new RegexBasedInterpolator("\\@\\{(", ")?([^}]+)\\}@");
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
@@ -136,10 +117,10 @@ public void testUseAlternateRegex() throws Exception {
     }
 
     @Test
-    public void testNPEFree() throws Exception {
+    void npeFree() throws Exception {
         RegexBasedInterpolator rbi = new RegexBasedInterpolator("\\@\\{(", ")?([^}]+)\\}@");
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
@@ -150,19 +131,15 @@ public void testNPEFree() throws Exception {
     }
 
     @Test
-    public void testUsePostProcessor_DoesNotChangeValue() throws InterpolationException {
+    void usePostProcessorDoesNotChangeValue() throws Exception {
         RegexBasedInterpolator rbi = new RegexBasedInterpolator();
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("test.var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
 
-        rbi.addPostProcessor(new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return null;
-            }
-        });
+        rbi.addPostProcessor((expression, value) -> null);
 
         String result = rbi.interpolate("this is a ${test.var}", "");
 
@@ -170,7 +147,7 @@ public Object execute(String expression, Object value) {
     }
 
     @Test
-    public void testUsePostProcessor_ChangesValue() throws InterpolationException {
+    void usePostProcessorChangesValue() throws Exception {
 
         int loopNumber = 200000;
 
@@ -178,16 +155,12 @@ public void testUsePostProcessor_ChangesValue() throws InterpolationException {
 
         RegexBasedInterpolator rbi = new RegexBasedInterpolator();
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("test.var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
 
-        rbi.addPostProcessor(new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return value + "2";
-            }
-        });
+        rbi.addPostProcessor((expression, value) -> value + "2");
 
         for (int i = 0, number = loopNumber; i < number; i++) {
 
@@ -205,11 +178,7 @@ public Object execute(String expression, Object value) {
 
         rbi = new RegexBasedInterpolator(true);
 
-        rbi.addPostProcessor(new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return value + "2";
-            }
-        });
+        rbi.addPostProcessor((expression, value) -> value + "2");
 
         rbi.addValueSource(new MapBasedValueSource(context));
 
@@ -225,8 +194,8 @@ public Object execute(String expression, Object value) {
     }
 
     @Test
-    public void testCacheAnswersTrue() throws InterpolationException {
-        Map ctx = new HashMap();
+    void cacheAnswersTrue() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("key", "value");
 
         final int[] valueSourceCallCount = {0};
@@ -260,8 +229,8 @@ public Object getValue(String expression) {
     }
 
     @Test
-    public void testCacheAnswersFalse() throws InterpolationException {
-        Map ctx = new HashMap();
+    void cacheAnswersFalse() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("key", "value");
 
         final int[] valueSourceCallCount = {0};
diff --git a/src/test/java/org/codehaus/plexus/interpolation/StringSearchInterpolatorTest.java b/src/test/java/org/codehaus/plexus/interpolation/StringSearchInterpolatorTest.java
index e1fa00a..e96c91c 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/StringSearchInterpolatorTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/StringSearchInterpolatorTest.java
@@ -1,22 +1,5 @@
 package org.codehaus.plexus.interpolation;
 
-/*
- * Copyright 2001-2008 Codehaus Foundation.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -34,12 +17,12 @@
 public class StringSearchInterpolatorTest {
 
     @BeforeEach
-    public void setUp() {
+    void setUp() {
         EnvarBasedValueSource.resetStatics();
     }
 
     @Test
-    public void testLongDelimitersInContext() throws InterpolationException {
+    void longDelimitersInContext() throws Exception {
         String src = "This is a <expression>test.label</expression> for long delimiters in context.";
         String result = "This is a test for long delimiters in context.";
 
@@ -53,7 +36,7 @@ public void testLongDelimitersInContext() throws InterpolationException {
     }
 
     @Test
-    public void testLongDelimitersWithNoStartContext() throws InterpolationException {
+    void longDelimitersWithNoStartContext() throws Exception {
         String src = "<expression>test.label</expression> for long delimiters in context.";
         String result = "test for long delimiters in context.";
 
@@ -67,7 +50,7 @@ public void testLongDelimitersWithNoStartContext() throws InterpolationException
     }
 
     @Test
-    public void testLongDelimitersWithNoEndContext() throws InterpolationException {
+    void longDelimitersWithNoEndContext() throws Exception {
         String src = "This is a <expression>test.label</expression>";
         String result = "This is a test";
 
@@ -81,7 +64,7 @@ public void testLongDelimitersWithNoEndContext() throws InterpolationException {
     }
 
     @Test
-    public void testLongDelimitersWithNoContext() throws InterpolationException {
+    void longDelimitersWithNoContext() throws Exception {
         String src = "<expression>test.label</expression>";
         String result = "test";
 
@@ -95,7 +78,7 @@ public void testLongDelimitersWithNoContext() throws InterpolationException {
     }
 
     @Test
-    public void testLongDelimitersPassedToValueSource() throws InterpolationException {
+    void longDelimitersPassedToValueSource() throws Exception {
         String src = "<expression>test</expression>";
 
         StringSearchInterpolator interpolator = new StringSearchInterpolator("<expression>", "</expression>");
@@ -119,7 +102,7 @@ public Object getValue(String expression) {
     }
 
     @Test
-    public void testSimpleSubstitution() throws InterpolationException {
+    void simpleSubstitution() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -130,7 +113,7 @@ public void testSimpleSubstitution() throws InterpolationException {
     }
 
     @Test
-    public void testSimpleSubstitution_TwoExpressions() throws InterpolationException {
+    void simpleSubstitutionTwoExpressions() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
@@ -142,7 +125,7 @@ public void testSimpleSubstitution_TwoExpressions() throws InterpolationExceptio
     }
 
     @Test
-    public void testBrokenExpression_LeaveItAlone() throws InterpolationException {
+    void brokenExpressionLeaveItAlone() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -153,7 +136,7 @@ public void testBrokenExpression_LeaveItAlone() throws InterpolationException {
     }
 
     @Test
-    public void testShouldFailOnExpressionCycle() {
+    void shouldFailOnExpressionCycle() {
         Properties props = new Properties();
         props.setProperty("key1", "${key2}");
         props.setProperty("key2", "${key1}");
@@ -171,7 +154,7 @@ public void testShouldFailOnExpressionCycle() {
     }
 
     @Test
-    public void testShouldResolveByUsingObject_List_Map() throws InterpolationException {
+    void shouldResolveByUsingObjectListMap() throws Exception {
         StringSearchInterpolator rbi = new StringSearchInterpolator();
         rbi.addValueSource(new ObjectBasedValueSource(this));
         String result =
@@ -181,10 +164,10 @@ public void testShouldResolveByUsingObject_List_Map() throws InterpolationExcept
     }
 
     @Test
-    public void testShouldResolveByContextValue() throws InterpolationException {
+    void shouldResolveByContextValue() throws Exception {
         StringSearchInterpolator rbi = new StringSearchInterpolator();
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
@@ -195,14 +178,12 @@ public void testShouldResolveByContextValue() throws InterpolationException {
     }
 
     @Test
-    public void testShouldResolveByEnvar() throws IOException, InterpolationException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("SOME_ENV", "variable");
-                map.put("OTHER_ENV", "other variable");
-                return map;
-            }
+    void shouldResolveByEnvar() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("SOME_ENV", "variable");
+            map.put("OTHER_ENV", "other variable");
+            return map;
         });
 
         StringSearchInterpolator rbi = new StringSearchInterpolator();
@@ -215,19 +196,15 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    public void testUsePostProcessor_DoesNotChangeValue() throws InterpolationException {
+    void usePostProcessorDoesNotChangeValue() throws Exception {
         StringSearchInterpolator rbi = new StringSearchInterpolator();
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("test.var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
 
-        rbi.addPostProcessor(new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return null;
-            }
-        });
+        rbi.addPostProcessor((expression, value) -> null);
 
         String result = rbi.interpolate("this is a ${test.var}");
 
@@ -235,20 +212,16 @@ public Object execute(String expression, Object value) {
     }
 
     @Test
-    public void testUsePostProcessor_ChangesValue() throws InterpolationException {
+    void usePostProcessorChangesValue() throws Exception {
 
         StringSearchInterpolator rbi = new StringSearchInterpolator();
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("test.var", "testVar");
 
         rbi.addValueSource(new MapBasedValueSource(context));
 
-        rbi.addPostProcessor(new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return value + "2";
-            }
-        });
+        rbi.addPostProcessor((expression, value) -> value + "2");
 
         String result = rbi.interpolate("this is a ${test.var}");
 
@@ -256,7 +229,7 @@ public Object execute(String expression, Object value) {
     }
 
     @Test
-    public void testSimpleSubstitutionWithDefinedExpr() throws InterpolationException {
+    void simpleSubstitutionWithDefinedExpr() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -267,7 +240,7 @@ public void testSimpleSubstitutionWithDefinedExpr() throws InterpolationExceptio
     }
 
     @Test
-    public void testEscape() throws InterpolationException {
+    void escape() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -281,7 +254,7 @@ public void testEscape() throws InterpolationException {
     }
 
     @Test
-    public void testEscapeWithLongEscapeStr() throws InterpolationException {
+    void escapeWithLongEscapeStr() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -295,7 +268,7 @@ public void testEscapeWithLongEscapeStr() throws InterpolationException {
     }
 
     @Test
-    public void testEscapeWithLongEscapeStrAtStart() throws InterpolationException {
+    void escapeWithLongEscapeStrAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -309,7 +282,7 @@ public void testEscapeWithLongEscapeStrAtStart() throws InterpolationException {
     }
 
     @Test
-    public void testNotEscapeWithLongEscapeStrAtStart() throws InterpolationException {
+    void notEscapeWithLongEscapeStrAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -323,7 +296,7 @@ public void testNotEscapeWithLongEscapeStrAtStart() throws InterpolationExceptio
     }
 
     @Test
-    public void testEscapeNotFailWithNullEscapeStr() throws InterpolationException {
+    void escapeNotFailWithNullEscapeStr() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -337,7 +310,7 @@ public void testEscapeNotFailWithNullEscapeStr() throws InterpolationException {
     }
 
     @Test
-    public void testOnlyEscapeExprAtStart() throws InterpolationException {
+    void onlyEscapeExprAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -351,7 +324,7 @@ public void testOnlyEscapeExprAtStart() throws InterpolationException {
     }
 
     @Test
-    public void testNotEscapeExprAtStart() throws InterpolationException {
+    void notEscapeExprAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -365,7 +338,7 @@ public void testNotEscapeExprAtStart() throws InterpolationException {
     }
 
     @Test
-    public void testEscapeExprAtStart() throws InterpolationException {
+    void escapeExprAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -379,7 +352,7 @@ public void testEscapeExprAtStart() throws InterpolationException {
     }
 
     @Test
-    public void testNPEFree() throws InterpolationException {
+    void npeFree() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -393,7 +366,7 @@ public void testNPEFree() throws InterpolationException {
     }
 
     @Test
-    public void testInterruptedInterpolate() throws InterpolationException {
+    void interruptedInterpolate() throws Exception {
         Interpolator interpolator = new StringSearchInterpolator();
         RecursionInterceptor recursionInterceptor = new SimpleRecursionInterceptor();
         final boolean[] error = new boolean[] {false};
@@ -431,7 +404,7 @@ public void clearFeedback() {}
     }
 
     @Test
-    public void testCacheAnswersTrue() throws InterpolationException {
+    void cacheAnswersTrue() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -470,7 +443,7 @@ public int getExistingCallCount() {
     }
 
     @Test
-    public void testCacheAnswersFalse() throws InterpolationException {
+    void cacheAnswersFalse() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -514,7 +487,7 @@ public Person[] getAnArray() {
     }
 
     public List<Person> getList() {
-        List<Person> list = new ArrayList<Person>();
+        List<Person> list = new ArrayList<>();
         list.add(new Person("Gabriel"));
         list.add(new Person("testIndexedWithList"));
         list.add(new Person("Daniela"));
@@ -522,13 +495,13 @@ public List<Person> getList() {
     }
 
     public Map<String, Person> getMap() {
-        Map<String, Person> map = new HashMap<String, StringSearchInterpolatorTest.Person>();
+        Map<String, Person> map = new HashMap<>();
         map.put("Key with spaces", new Person("testMap"));
         return map;
     }
 
     public static class Person {
-        private String name;
+        private final String name;
 
         public Person(String name) {
             this.name = name;
diff --git a/src/test/java/org/codehaus/plexus/interpolation/fixed/EnvarBasedValueSourceTest.java b/src/test/java/org/codehaus/plexus/interpolation/fixed/EnvarBasedValueSourceTest.java
index b6ff638..8ae7bd6 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/fixed/EnvarBasedValueSourceTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/fixed/EnvarBasedValueSourceTest.java
@@ -16,9 +16,7 @@
  * limitations under the License.
  */
 
-import java.io.IOException;
 import java.util.HashMap;
-import java.util.Map;
 
 import org.codehaus.plexus.interpolation.os.OperatingSystemUtils;
 import org.junit.jupiter.api.BeforeEach;
@@ -28,21 +26,19 @@
 import static org.junit.jupiter.api.Assertions.assertNotNull;
 import static org.junit.jupiter.api.Assertions.assertNull;
 
-public class EnvarBasedValueSourceTest {
+class EnvarBasedValueSourceTest {
 
     @BeforeEach
-    public void setUp() {
+    void setUp() {
         EnvarBasedValueSource.resetStatics();
     }
 
     @Test
-    void testNoArgConstructorIsCaseSensitive() throws IOException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("aVariable", "variable");
-                return map;
-            }
+    void noArgConstructorIsCaseSensitive() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("aVariable", "variable");
+            return map;
         });
 
         EnvarBasedValueSource source = new EnvarBasedValueSource();
@@ -54,13 +50,11 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    void testCaseInsensitive() throws IOException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("aVariable", "variable");
-                return map;
-            }
+    void caseInsensitive() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("aVariable", "variable");
+            return map;
         });
 
         EnvarBasedValueSource source = new EnvarBasedValueSource(false);
@@ -72,7 +66,7 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    void testGetRealEnvironmentVariable() throws IOException {
+    void getRealEnvironmentVariable() throws Exception {
         OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.DefaultEnvVarSource());
 
         EnvarBasedValueSource source = new EnvarBasedValueSource();
diff --git a/src/test/java/org/codehaus/plexus/interpolation/fixed/FixedStringSearchInterpolatorTest.java b/src/test/java/org/codehaus/plexus/interpolation/fixed/FixedStringSearchInterpolatorTest.java
index afef83e..2061736 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/fixed/FixedStringSearchInterpolatorTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/fixed/FixedStringSearchInterpolatorTest.java
@@ -15,7 +15,6 @@
  * limitations under the License.
  */
 
-import java.io.IOException;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
@@ -23,7 +22,6 @@
 import java.util.Properties;
 
 import org.codehaus.plexus.interpolation.FixedInterpolatorValueSource;
-import org.codehaus.plexus.interpolation.InterpolationException;
 import org.codehaus.plexus.interpolation.InterpolationPostProcessor;
 import org.codehaus.plexus.interpolation.StringSearchInterpolator;
 import org.codehaus.plexus.interpolation.os.OperatingSystemUtils;
@@ -37,12 +35,12 @@
 public class FixedStringSearchInterpolatorTest {
 
     @BeforeEach
-    public void setUp() {
+    void setUp() {
         EnvarBasedValueSource.resetStatics();
     }
 
     @Test
-    void testLongDelimitersInContext() {
+    void longDelimitersInContext() {
         String src = "This is a <expression>test.label</expression> for long delimiters in context.";
         String result = "This is a test for long delimiters in context.";
 
@@ -56,7 +54,7 @@ void testLongDelimitersInContext() {
     }
 
     @Test
-    void testLongDelimitersWithNoStartContext() {
+    void longDelimitersWithNoStartContext() {
         String src = "<expression>test.label</expression> for long delimiters in context.";
         String result = "test for long delimiters in context.";
 
@@ -70,7 +68,7 @@ void testLongDelimitersWithNoStartContext() {
     }
 
     @Test
-    void testLongDelimitersWithNoEndContext() {
+    void longDelimitersWithNoEndContext() {
         String src = "This is a <expression>test.label</expression>";
         String result = "This is a test";
 
@@ -84,7 +82,7 @@ void testLongDelimitersWithNoEndContext() {
     }
 
     @Test
-    void testLongDelimitersWithNoContext() {
+    void longDelimitersWithNoContext() {
         String src = "<expression>test.label</expression>";
         String result = "test";
 
@@ -98,7 +96,7 @@ void testLongDelimitersWithNoContext() {
     }
 
     @Test
-    void testSimpleSubstitution() {
+    void simpleSubstitution() {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -108,7 +106,7 @@ void testSimpleSubstitution() {
     }
 
     @Test
-    void testSimpleSubstitution_TwoExpressions() {
+    void simpleSubstitutionTwoExpressions() {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
@@ -119,7 +117,7 @@ void testSimpleSubstitution_TwoExpressions() {
     }
 
     @Test
-    void testBrokenExpression_LeaveItAlone() {
+    void brokenExpressionLeaveItAlone() {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -129,7 +127,7 @@ void testBrokenExpression_LeaveItAlone() {
     }
 
     @Test
-    void testShouldFailOnExpressionCycle() {
+    void shouldFailOnExpressionCycle() {
         Properties props = new Properties();
         props.setProperty("key1", "${key2}");
         props.setProperty("key2", "${key1}");
@@ -143,7 +141,7 @@ void testShouldFailOnExpressionCycle() {
     }
 
     @Test
-    void testShouldResolveByUsingObject_List_Map() throws InterpolationException {
+    void shouldResolveByUsingObjectListMap() throws Exception {
         FixedStringSearchInterpolator rbi = create(new ObjectBasedValueSource(this));
         String result =
                 rbi.interpolate("this is a ${var} ${list[1].name} ${anArray[2].name} ${map(Key with spaces).name}");
@@ -152,9 +150,9 @@ void testShouldResolveByUsingObject_List_Map() throws InterpolationException {
     }
 
     @Test
-    void testShouldResolveByContextValue() throws InterpolationException {
+    void shouldResolveByContextValue() throws Exception {
 
-        Map<String, String> context = new HashMap<String, String>();
+        Map<String, String> context = new HashMap<>();
         context.put("var", "testVar");
 
         FixedStringSearchInterpolator rbi = create(new MapBasedValueSource(context));
@@ -165,14 +163,12 @@ void testShouldResolveByContextValue() throws InterpolationException {
     }
 
     @Test
-    void testShouldResolveByEnvar() throws IOException, InterpolationException {
-        OperatingSystemUtils.setEnvVarSource(new OperatingSystemUtils.EnvVarSource() {
-            public Map<String, String> getEnvMap() {
-                HashMap<String, String> map = new HashMap<String, String>();
-                map.put("SOME_ENV", "variable");
-                map.put("OTHER_ENV", "other variable");
-                return map;
-            }
+    void shouldResolveByEnvar() throws Exception {
+        OperatingSystemUtils.setEnvVarSource(() -> {
+            HashMap<String, String> map = new HashMap<>();
+            map.put("SOME_ENV", "variable");
+            map.put("OTHER_ENV", "other variable");
+            return map;
         });
 
         FixedStringSearchInterpolator rbi = create(new EnvarBasedValueSource(false));
@@ -183,16 +179,12 @@ public Map<String, String> getEnvMap() {
     }
 
     @Test
-    void testUsePostProcessor_DoesNotChangeValue() throws InterpolationException {
+    void usePostProcessorDoesNotChangeValue() throws Exception {
 
-        Map<String, String> context = new HashMap<String, String>();
+        Map<String, String> context = new HashMap<>();
         context.put("test.var", "testVar");
 
-        final InterpolationPostProcessor postProcessor = new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return null;
-            }
-        };
+        InterpolationPostProcessor postProcessor = (expression, value) -> null;
         FixedStringSearchInterpolator rbi =
                 create(new MapBasedValueSource(context)).withPostProcessor(postProcessor);
 
@@ -202,16 +194,12 @@ public Object execute(String expression, Object value) {
     }
 
     @Test
-    void testUsePostProcessor_ChangesValue() throws InterpolationException {
+    void usePostProcessorChangesValue() throws Exception {
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("test.var", "testVar");
 
-        final InterpolationPostProcessor postProcessor = new InterpolationPostProcessor() {
-            public Object execute(String expression, Object value) {
-                return value + "2";
-            }
-        };
+        InterpolationPostProcessor postProcessor = (expression, value) -> value + "2";
 
         FixedStringSearchInterpolator rbi =
                 create(new MapBasedValueSource(context)).withPostProcessor(postProcessor);
@@ -222,7 +210,7 @@ public Object execute(String expression, Object value) {
     }
 
     @Test
-    void testSimpleSubstitutionWithDefinedExpr() throws InterpolationException {
+    void simpleSubstitutionWithDefinedExpr() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -232,7 +220,7 @@ void testSimpleSubstitutionWithDefinedExpr() throws InterpolationException {
     }
 
     @Test
-    void testEscape() throws InterpolationException {
+    void escape() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -246,7 +234,7 @@ void testEscape() throws InterpolationException {
     }
 
     @Test
-    void testEscapeWithLongEscapeStr() throws InterpolationException {
+    void escapeWithLongEscapeStr() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -260,7 +248,7 @@ void testEscapeWithLongEscapeStr() throws InterpolationException {
     }
 
     @Test
-    void testEscapeWithLongEscapeStrAtStart() throws InterpolationException {
+    void escapeWithLongEscapeStrAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -274,7 +262,7 @@ void testEscapeWithLongEscapeStrAtStart() throws InterpolationException {
     }
 
     @Test
-    void testNotEscapeWithLongEscapeStrAtStart() throws InterpolationException {
+    void notEscapeWithLongEscapeStrAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -288,7 +276,7 @@ void testNotEscapeWithLongEscapeStrAtStart() throws InterpolationException {
     }
 
     @Test
-    void testEscapeNotFailWithNullEscapeStr() throws InterpolationException {
+    void escapeNotFailWithNullEscapeStr() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -302,7 +290,7 @@ void testEscapeNotFailWithNullEscapeStr() throws InterpolationException {
     }
 
     @Test
-    void testOnlyEscapeExprAtStart() throws InterpolationException {
+    void onlyEscapeExprAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -316,7 +304,7 @@ void testOnlyEscapeExprAtStart() throws InterpolationException {
     }
 
     @Test
-    void testNotEscapeExprAtStart() throws InterpolationException {
+    void notEscapeExprAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -330,7 +318,7 @@ void testNotEscapeExprAtStart() throws InterpolationException {
     }
 
     @Test
-    void testEscapeExprAtStart() throws InterpolationException {
+    void escapeExprAtStart() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -344,7 +332,7 @@ void testEscapeExprAtStart() throws InterpolationException {
     }
 
     @Test
-    void testNPEFree() throws InterpolationException {
+    void npeFree() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
 
@@ -358,18 +346,16 @@ void testNPEFree() throws InterpolationException {
     }
 
     @Test
-    void testInterruptedInterpolate() throws InterpolationException {
+    void interruptedInterpolate() throws Exception {
         final boolean[] error = new boolean[] {false};
-        FixedValueSource valueSource = new FixedValueSource() {
-            public Object getValue(String expression, InterpolationState errorCollector) {
-                if (expression.equals("key")) {
-                    if (error[0]) {
-                        throw new IllegalStateException("broken");
-                    }
-                    return "val";
-                } else {
-                    return null;
+        FixedValueSource valueSource = (expression, errorCollector) -> {
+            if (expression.equals("key")) {
+                if (error[0]) {
+                    throw new IllegalStateException("broken");
                 }
+                return "val";
+            } else {
+                return null;
             }
         };
 
@@ -400,7 +386,7 @@ public Person[] getAnArray() {
     }
 
     public List<Person> getList() {
-        List<Person> list = new ArrayList<Person>();
+        List<Person> list = new ArrayList<>();
         list.add(new Person("Gabriel"));
         list.add(new Person("testIndexedWithList"));
         list.add(new Person("Daniela"));
@@ -408,13 +394,13 @@ public List<Person> getList() {
     }
 
     public Map<String, Person> getMap() {
-        Map<String, Person> map = new HashMap<String, Person>();
+        Map<String, Person> map = new HashMap<>();
         map.put("Key with spaces", new Person("testMap"));
         return map;
     }
 
     public static class Person {
-        private String name;
+        private final String name;
 
         public Person(String name) {
             this.name = name;
@@ -426,7 +412,7 @@ public String getName() {
     }
 
     @Test
-    void testLinkedInterpolators() {
+    void linkedInterpolators() {
         final String EXPR = "${test.label}AND${test2}";
         final String EXPR2 = "${test.label}${test2.label}AND${test2}";
 
@@ -439,7 +425,7 @@ void testLinkedInterpolators() {
     }
 
     @Test
-    void testDominance() {
+    void dominance() {
         final String EXPR = "${test.label}AND${test2}";
         final String EXPR2 = "${test.label}${test2.label}AND${test2}";
 
@@ -463,25 +449,21 @@ void unresolable_linked() {
     }
 
     @Test
-    void testCyclesWithLinked() {
-        assertThrows(InterpolationCycleException.class, () -> {
-            FixedStringSearchInterpolator first = create(properttyBasedValueSource("key1", "${key2}"));
-            FixedStringSearchInterpolator second = create(first, properttyBasedValueSource("key2", "${key1}"));
-            second.interpolate("${key2}");
-        });
+    void cyclesWithLinked() {
+        FixedStringSearchInterpolator first = create(properttyBasedValueSource("key1", "${key2}"));
+        FixedStringSearchInterpolator second = create(first, properttyBasedValueSource("key2", "${key1}"));
+        assertThrows(InterpolationCycleException.class, () -> second.interpolate("${key2}"));
     }
 
     @Test
-    void testCyclesWithLinked_betweenRootAndOther() {
-        assertThrows(InterpolationCycleException.class, () -> {
-            FixedStringSearchInterpolator first = create(properttyBasedValueSource("key1", "${key2}"));
-            FixedStringSearchInterpolator second = create(first, properttyBasedValueSource("key2", "${key1}"));
-            second.interpolate("${key1}");
-        });
+    void cyclesWithLinkedBetweenRootAndOther() {
+        FixedStringSearchInterpolator first = create(properttyBasedValueSource("key1", "${key2}"));
+        FixedStringSearchInterpolator second = create(first, properttyBasedValueSource("key2", "${key1}"));
+        assertThrows(InterpolationCycleException.class, () -> second.interpolate("${key1}"));
     }
 
     @Test
-    void fixedInjectedIntoRegular() throws InterpolationException {
+    void fixedInjectedIntoRegular() throws Exception {
         FixedStringSearchInterpolator first = create(properttyBasedValueSource("key1", "v1"));
 
         Properties p = new Properties();
diff --git a/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterInterpolatorFilterReaderTest.java b/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterInterpolatorFilterReaderTest.java
index 95ab97d..bb2b026 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterInterpolatorFilterReaderTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterInterpolatorFilterReaderTest.java
@@ -46,14 +46,14 @@
  * @author cstamas
  *
  */
-public class MultiDelimiterInterpolatorFilterReaderTest {
+class MultiDelimiterInterpolatorFilterReaderTest {
     /*
      * Added and commented by jdcasey@03-Feb-2005 because it is a bug in the InterpolationFilterReader.
      * kenneyw@15-04-2005 fixed the bug.
      */
     @Test
-    public void testShouldNotInterpolateExpressionAtEndOfDataWithInvalidEndToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateExpressionAtEndOfDataWithInvalidEndToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "TestValue");
 
         String testStr = "This is a ${test";
@@ -65,8 +65,8 @@ public void testShouldNotInterpolateExpressionAtEndOfDataWithInvalidEndToken() t
      * kenneyw@14-04-2005 Added test to check above fix.
      */
     @Test
-    public void testShouldNotInterpolateExpressionWithMissingEndToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateExpressionWithMissingEndToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "TestValue");
 
         String testStr = "This is a ${test, really";
@@ -75,8 +75,8 @@ public void testShouldNotInterpolateExpressionWithMissingEndToken() throws Excep
     }
 
     @Test
-    public void testShouldNotInterpolateWithMalformedStartToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateWithMalformedStartToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "testValue");
 
         String foo = "This is a $!test} again";
@@ -85,8 +85,8 @@ public void testShouldNotInterpolateWithMalformedStartToken() throws Exception {
     }
 
     @Test
-    public void testShouldNotInterpolateWithMalformedEndToken() throws Exception {
-        Map m = new HashMap();
+    void shouldNotInterpolateWithMalformedEndToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("test", "testValue");
 
         String foo = "This is a ${test!} again";
@@ -95,8 +95,8 @@ public void testShouldNotInterpolateWithMalformedEndToken() throws Exception {
     }
 
     @Test
-    public void testDefaultInterpolationWithNonInterpolatedValueAtEnd() throws Exception {
-        Map m = new HashMap();
+    void defaultInterpolationWithNonInterpolatedValueAtEnd() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -106,8 +106,8 @@ public void testDefaultInterpolationWithNonInterpolatedValueAtEnd() throws Excep
     }
 
     @Test
-    public void testDefaultInterpolationWithInterpolatedValueAtEnd() throws Exception {
-        Map m = new HashMap();
+    void defaultInterpolationWithInterpolatedValueAtEnd() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -117,8 +117,8 @@ public void testDefaultInterpolationWithInterpolatedValueAtEnd() throws Exceptio
     }
 
     @Test
-    public void testInterpolationWithInterpolatedValueAtEndWithCustomToken() throws Exception {
-        Map m = new HashMap();
+    void interpolationWithInterpolatedValueAtEndWithCustomToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -128,8 +128,8 @@ public void testInterpolationWithInterpolatedValueAtEndWithCustomToken() throws
     }
 
     @Test
-    public void testInterpolationWithInterpolatedValueAtEndWithCustomTokenAndCustomString() throws Exception {
-        Map m = new HashMap();
+    void interpolationWithInterpolatedValueAtEndWithCustomTokenAndCustomString() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -139,8 +139,8 @@ public void testInterpolationWithInterpolatedValueAtEndWithCustomTokenAndCustomS
     }
 
     @Test
-    public void testEscape() throws Exception {
-        Map m = new HashMap();
+    void escape() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -150,8 +150,8 @@ public void testEscape() throws Exception {
     }
 
     @Test
-    public void testEscapeAtStart() throws Exception {
-        Map m = new HashMap();
+    void escapeAtStart() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -161,8 +161,8 @@ public void testEscapeAtStart() throws Exception {
     }
 
     @Test
-    public void testEscapeOnlyAtStart() throws Exception {
-        Map m = new HashMap();
+    void escapeOnlyAtStart() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -173,8 +173,8 @@ public void testEscapeOnlyAtStart() throws Exception {
     }
 
     @Test
-    public void testEscapeOnlyAtStartDefaultToken() throws Exception {
-        Map m = new HashMap();
+    void escapeOnlyAtStartDefaultToken() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("noun", "asshole");
 
@@ -185,15 +185,15 @@ public void testEscapeOnlyAtStartDefaultToken() throws Exception {
     }
 
     @Test
-    public void testShouldDetectRecursiveExpressionPassingThroughTwoPrefixes() throws Exception {
-        List prefixes = new ArrayList();
+    void shouldDetectRecursiveExpressionPassingThroughTwoPrefixes() throws Exception {
+        List<String> prefixes = new ArrayList<>();
 
         prefixes.add("prefix1");
         prefixes.add("prefix2");
 
         RecursionInterceptor ri = new PrefixAwareRecursionInterceptor(prefixes, false);
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("name", "${prefix2.name}");
 
         String input = "${prefix1.name}";
@@ -217,14 +217,14 @@ public void testShouldDetectRecursiveExpressionPassingThroughTwoPrefixes() throw
     }
 
     @Test
-    public void testShouldDetectRecursiveExpressionWithPrefixAndWithout() throws Exception {
-        List prefixes = new ArrayList();
+    void shouldDetectRecursiveExpressionWithPrefixAndWithout() throws Exception {
+        List<String> prefixes = new ArrayList<>();
 
         prefixes.add("prefix1");
 
         RecursionInterceptor ri = new PrefixAwareRecursionInterceptor(prefixes, false);
 
-        Map context = new HashMap();
+        Map<String, String> context = new HashMap<>();
         context.put("name", "${prefix1.name}");
 
         String input = "${name}";
@@ -248,8 +248,8 @@ public void testShouldDetectRecursiveExpressionWithPrefixAndWithout() throws Exc
     }
 
     @Test
-    public void testInterpolationWithMultipleTokenTypes() throws Exception {
-        Map m = new HashMap();
+    void interpolationWithMultipleTokenTypes() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("otherName", "@name@");
 
@@ -259,8 +259,8 @@ public void testInterpolationWithMultipleTokenTypes() throws Exception {
     }
 
     @Test
-    public void testInterpolationWithMultipleTokenTypes_ReversedOrdering() throws Exception {
-        Map m = new HashMap();
+    void interpolationWithMultipleTokenTypesReversedOrdering() throws Exception {
+        Map<String, String> m = new HashMap<>();
         m.put("name", "jason");
         m.put("otherName", "${name}");
 
@@ -273,11 +273,11 @@ public void testInterpolationWithMultipleTokenTypes_ReversedOrdering() throws Ex
     //
     // ----------------------------------------------------------------------
 
-    private String interpolate(String input, Map context) throws Exception {
+    private String interpolate(String input, Map<String, String> context) throws Exception {
         return interpolate(input, context, null);
     }
 
-    private String interpolate(String input, Map context, String escapeStr) throws Exception {
+    private String interpolate(String input, Map<String, String> context, String escapeStr) throws Exception {
         Interpolator interpolator = new StringSearchInterpolator();
 
         interpolator.addValueSource(new MapBasedValueSource(context));
@@ -298,7 +298,8 @@ private String interpolate(String input, Map context, String escapeStr) throws E
         return buf.toString();
     }
 
-    private String interpolate(String input, Map context, String beginToken, String endToken) throws Exception {
+    private String interpolate(String input, Map<String, String> context, String beginToken, String endToken)
+            throws Exception {
         StringSearchInterpolator interpolator = new StringSearchInterpolator(beginToken, endToken);
 
         interpolator.addValueSource(new MapBasedValueSource(context));
@@ -319,7 +320,7 @@ private String interpolate(String input, Map context, String beginToken, String
         return buf.toString();
     }
 
-    private String interpolateMulti(String input, Map context, String[] specs) throws Exception {
+    private String interpolateMulti(String input, Map<String, String> context, String[] specs) throws Exception {
         MultiDelimiterStringSearchInterpolator interp = new MultiDelimiterStringSearchInterpolator();
         interp.addValueSource(new MapBasedValueSource(context));
 
diff --git a/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolatorTest.java b/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolatorTest.java
index 7b38a16..6f96f98 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolatorTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/multi/MultiDelimiterStringSearchInterpolatorTest.java
@@ -20,7 +20,6 @@
 import java.util.Map;
 
 import org.codehaus.plexus.interpolation.AbstractValueSource;
-import org.codehaus.plexus.interpolation.InterpolationException;
 import org.codehaus.plexus.interpolation.MapBasedValueSource;
 import org.codehaus.plexus.interpolation.ValueSource;
 import org.junit.jupiter.api.Test;
@@ -28,11 +27,11 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.fail;
 
-public class MultiDelimiterStringSearchInterpolatorTest {
+class MultiDelimiterStringSearchInterpolatorTest {
 
     @Test
-    public void testInterpolationWithDifferentDelimiters() throws InterpolationException {
-        Map ctx = new HashMap();
+    void interpolationWithDifferentDelimiters() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("name", "User");
         ctx.put("otherName", "@name@");
 
@@ -49,9 +48,8 @@ public void testInterpolationWithDifferentDelimiters() throws InterpolationExcep
     }
 
     @Test
-    public void testSuccessiveInterpolationWithDifferentDelimiters_ReversedDelimiterSequence()
-            throws InterpolationException {
-        Map ctx = new HashMap();
+    void successiveInterpolationWithDifferentDelimitersReversedDelimiterSequence() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("name", "User");
         ctx.put("otherName", "${name}");
 
@@ -68,8 +66,8 @@ public void testSuccessiveInterpolationWithDifferentDelimiters_ReversedDelimiter
     }
 
     @Test
-    public void testInterpolationWithMultipleEscapes() throws InterpolationException {
-        Map ctx = new HashMap();
+    void interpolationWithMultipleEscapes() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("name", "User");
         ctx.put("otherName", "##${first} and #${last}");
 
@@ -86,8 +84,8 @@ public void testInterpolationWithMultipleEscapes() throws InterpolationException
     }
 
     @Test
-    public void testInterpolationWithMultipleEscapes2() throws InterpolationException {
-        Map ctx = new HashMap();
+    void interpolationWithMultipleEscapes2() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("name", "User");
         ctx.put("otherName", "#${first} and ##${last}");
 
@@ -104,8 +102,8 @@ public void testInterpolationWithMultipleEscapes2() throws InterpolationExceptio
     }
 
     @Test
-    public void testInterpolationWithMultipleEscapes3() throws InterpolationException {
-        Map ctx = new HashMap();
+    void interpolationWithMultipleEscapes3() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("name", "User");
         ctx.put("last", "beer");
         ctx.put("otherName", "###${first} and ##${second} and ${last}");
@@ -123,7 +121,7 @@ public void testInterpolationWithMultipleEscapes3() throws InterpolationExceptio
     }
 
     @Test
-    public void testDelimitersPassedToValueSource() throws InterpolationException {
+    void delimitersPassedToValueSource() throws Exception {
         ValueSource vs = new AbstractValueSource(false) {
 
             @Override
@@ -148,8 +146,8 @@ public Object getValue(String expression) {
     }
 
     @Test
-    public void testCacheAnswersTrue() throws InterpolationException {
-        Map ctx = new HashMap();
+    void cacheAnswersTrue() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("key", "value");
 
         final int[] valueSourceCallCount = {0};
@@ -180,8 +178,8 @@ public Object getValue(String expression) {
     }
 
     @Test
-    public void testCacheAnswersFalse() throws InterpolationException {
-        Map ctx = new HashMap();
+    void cacheAnswersFalse() throws Exception {
+        Map<String, String> ctx = new HashMap<>();
         ctx.put("key", "value");
 
         final int[] valueSourceCallCount = {0};
diff --git a/src/test/java/org/codehaus/plexus/interpolation/object/FieldBasedObjectInterpolatorTest.java b/src/test/java/org/codehaus/plexus/interpolation/object/FieldBasedObjectInterpolatorTest.java
index 08c8ad8..c207036 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/object/FieldBasedObjectInterpolatorTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/object/FieldBasedObjectInterpolatorTest.java
@@ -29,10 +29,10 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-public class FieldBasedObjectInterpolatorTest {
+class FieldBasedObjectInterpolatorTest {
 
     @Test
-    public void testInterpolateStringArray() throws Exception {
+    void interpolateStringArray() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
@@ -49,7 +49,7 @@ public void testInterpolateStringArray() throws Exception {
     }
 
     @Test
-    public void testInterpolateObjectWithStringArrayField() throws Exception {
+    void interpolateObjectWithStringArrayField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
@@ -68,12 +68,12 @@ public void testInterpolateObjectWithStringArrayField() throws Exception {
     }
 
     @Test
-    public void testInterpolateObjectWithStringListField() throws Exception {
+    void interpolateObjectWithStringListField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
 
-        List<String> values = new ArrayList<String>();
+        List<String> values = new ArrayList<>();
         values.add("${key}");
         values.add("${key2}");
 
@@ -89,12 +89,12 @@ public void testInterpolateObjectWithStringListField() throws Exception {
     }
 
     @Test
-    public void testInterpolateObjectWithStringListFieldAndOneLiteralValue() throws Exception {
+    void interpolateObjectWithStringListFieldAndOneLiteralValue() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
 
-        List<String> values = new ArrayList<String>();
+        List<String> values = new ArrayList<>();
         values.add("key");
         values.add("${key2}");
 
@@ -110,12 +110,12 @@ public void testInterpolateObjectWithStringListFieldAndOneLiteralValue() throws
     }
 
     @Test
-    public void testInterpolateObjectWithUnmodifiableStringListField() throws Exception {
+    void interpolateObjectWithUnmodifiableStringListField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
 
-        List values = Collections.unmodifiableList(Collections.singletonList("${key}"));
+        List<String> values = Collections.singletonList("${key}");
 
         ObjectWithListField obj = new ObjectWithListField(values);
 
@@ -128,14 +128,14 @@ public void testInterpolateObjectWithUnmodifiableStringListField() throws Except
     }
 
     @Test
-    public void testInterpolateObjectWithStringArrayListField() throws Exception {
+    void interpolateObjectWithStringArrayListField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
         p.setProperty("key3", "value3");
         p.setProperty("key4", "value4");
 
-        List<String[]> values = new ArrayList<String[]>();
+        List<String[]> values = new ArrayList<>();
         values.add(new String[] {"${key}", "${key2}"});
         values.add(new String[] {"${key3}", "${key4}"});
 
@@ -153,12 +153,12 @@ public void testInterpolateObjectWithStringArrayListField() throws Exception {
     }
 
     @Test
-    public void testInterpolateObjectWithStringToStringMapField() throws Exception {
+    void interpolateObjectWithStringToStringMapField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
 
-        Map<String, String> values = new HashMap<String, String>();
+        Map<String, String> values = new HashMap<>();
         values.put("key", "${key}");
         values.put("key2", "${key2}");
 
@@ -174,12 +174,12 @@ public void testInterpolateObjectWithStringToStringMapField() throws Exception {
     }
 
     @Test
-    public void testInterpolateObjectWithStringToStringMapFieldAndOneLiteralValue() throws Exception {
+    void interpolateObjectWithStringToStringMapFieldAndOneLiteralValue() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
 
-        Map<String, String> values = new HashMap<String, String>();
+        Map<String, String> values = new HashMap<>();
         values.put("key", "val");
         values.put("key2", "${key2}");
 
@@ -195,12 +195,12 @@ public void testInterpolateObjectWithStringToStringMapFieldAndOneLiteralValue()
     }
 
     @Test
-    public void testInterpolateObjectWithUnmodifiableStringToStringMapField() throws Exception {
+    void interpolateObjectWithUnmodifiableStringToStringMapField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
 
-        Map values = Collections.unmodifiableMap(Collections.singletonMap("key", "${key}"));
+        Map<String, String> values = Collections.singletonMap("key", "${key}");
 
         ObjectWithMapField obj = new ObjectWithMapField(values);
 
@@ -213,14 +213,14 @@ public void testInterpolateObjectWithUnmodifiableStringToStringMapField() throws
     }
 
     @Test
-    public void testInterpolateObjectWithStringToStringArrayMapField() throws Exception {
+    void interpolateObjectWithStringToStringArrayMapField() throws Exception {
         Properties p = new Properties();
         p.setProperty("key", "value");
         p.setProperty("key2", "value2");
         p.setProperty("key3", "value3");
         p.setProperty("key4", "value4");
 
-        Map<String, String[]> values = new HashMap<String, String[]>();
+        Map<String, String[]> values = new HashMap<>();
         values.put("key", new String[] {"${key}", "${key2}"});
         values.put("key2", new String[] {"${key3}", "${key4}"});
 
diff --git a/src/test/java/org/codehaus/plexus/interpolation/util/StringUtilsTest.java b/src/test/java/org/codehaus/plexus/interpolation/util/StringUtilsTest.java
index d788f63..e47766c 100644
--- a/src/test/java/org/codehaus/plexus/interpolation/util/StringUtilsTest.java
+++ b/src/test/java/org/codehaus/plexus/interpolation/util/StringUtilsTest.java
@@ -19,9 +19,9 @@
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
-public class StringUtilsTest {
+class StringUtilsTest {
     @Test
-    public void testCapitalizeFirstLetter() throws Exception {
+    void capitalizeFirstLetter() throws Exception {
         assertEquals("Abc", StringUtils.capitalizeFirstLetter("abc"));
         assertEquals("\u00cdce", StringUtils.capitalizeFirstLetter("\u00edce"));
         assertEquals("X", StringUtils.capitalizeFirstLetter("x"));