Add recipe SimplifySingleElementAnnotation (#5740)

* Add recipe SimplifySingleElementAnnotation

* Update rewrite-java/src/main/java/org/openrewrite/java/SimplifySingleElementAnnotation.java

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update rewrite-java/src/test/java/org/openrewrite/java/SimplifySingleElementAnnotationTest.java

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Update rewrite-java/src/test/java/org/openrewrite/java/SimplifySingleElementAnnotationTest.java

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

* Add some more tests for special cases

* Make exception for `J.Empty`

* Simplify single attribute annotations are removing attribute

---------

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>
Co-authored-by: Tim te Beek <timtebeek@gmail.com>
Co-authored-by: Tim te Beek <tim@moderne.io>

Author: 3 people

rewrite-java-test/src/test/java/org/openrewrite/java/RemoveAnnotationAttributeTest.java

@@ -87,4 +87,34 @@ class A {}
           )
         );
     }
+
+    @Test
+    void simplifyAfterRemoval() {
+        rewriteRun(
+          spec -> spec
+            .parser(JavaParser.fromJavaVersion()
+              .dependsOn(
+                """
+                  @interface Copyright {
+                      int year();
+                      String value();
+                  }
+                  """
+              )
+            )
+            .recipe(new RemoveAnnotationAttribute("Copyright", "year")),
+          java(
+            """
+              @Copyright(year = 2002, value = "Yoyodyne Propulsion Systems, Inc.")
+              class OscillationOverthruster {
+              }
+              """,
+            """
+              @Copyright("Yoyodyne Propulsion Systems, Inc.")
+              class OscillationOverthruster {
+              }
+              """
+          )
+        );
+    }
 }

rewrite-java/build.gradle.kts

@@ -71,6 +71,7 @@ dependencies {
     // For use in ClassGraphTypeMappingTest
     testRuntimeOnly("org.eclipse.persistence:org.eclipse.persistence.core:3.0.2")
     testRuntimeOnly("org.slf4j:jul-to-slf4j:1.7.+")
+    testRuntimeOnly("jakarta.validation:jakarta.validation-api:3.1.1")
 }
 
 tasks.withType<Javadoc>().configureEach {

rewrite-java/src/main/java/org/openrewrite/java/RemoveAnnotationAttribute.java

@@ -68,7 +68,7 @@ public J.Annotation visitAnnotation(J.Annotation annotation, ExecutionContext ct
 
                 AtomicBoolean didPassFirstAttribute = new AtomicBoolean(false);
                 AtomicBoolean shouldTrimNextPrefix = new AtomicBoolean(false);
-                return a.withArguments(ListUtils.map(a.getArguments(), arg -> {
+                J.Annotation withoutAttribute = a.withArguments(ListUtils.map(a.getArguments(), arg -> {
                     try {
                         if (arg instanceof J.Assignment) {
                             J.Assignment assignment = (J.Assignment) arg;
@@ -96,6 +96,12 @@ public J.Annotation visitAnnotation(J.Annotation annotation, ExecutionContext ct
 
                     return arg;
                 }));
+                if (a != withoutAttribute &&
+                        withoutAttribute.getArguments() != null &&
+                        withoutAttribute.getArguments().size() == 1) {
+                    doAfterVisit(new SimplifySingleElementAnnotation().getVisitor());
+                }
+                return withoutAttribute;
             }
         });
     }

rewrite-java/src/main/java/org/openrewrite/java/SimplifySingleElementAnnotation.java

@@ -0,0 +1,72 @@
+/*
+ * Copyright 2025 the original author or authors.
+ * <p>
+ * 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
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.
+ */
+package org.openrewrite.java;
+
+import org.openrewrite.ExecutionContext;
+import org.openrewrite.Recipe;
+import org.openrewrite.TreeVisitor;
+import org.openrewrite.internal.ListUtils;
+import org.openrewrite.java.tree.Expression;
+import org.openrewrite.java.tree.J;
+import org.openrewrite.java.tree.Space;
+
+import java.util.List;
+
+public class SimplifySingleElementAnnotation extends Recipe {
+
+    @Override
+    public String getDisplayName() {
+        return "Simplify single-element annotation";
+    }
+
+    @Override
+    public String getDescription() {
+        return "This recipe will remove the attribute `value` on single-element annotations. " +
+                "According to JLS, a _single-element annotation_, is a shorthand designed for use with single-element annotation types.";
+    }
+
+    @Override
+    public TreeVisitor<?, ExecutionContext> getVisitor() {
+        return new JavaIsoVisitor<ExecutionContext>() {
+            @Override
+            public J.Annotation visitAnnotation(J.Annotation annotation, ExecutionContext executionContext) {
+                J.Annotation an = super.visitAnnotation(annotation, executionContext);
+
+                if (an.getArguments() != null && an.getArguments().size() == 1) {
+                    an = an.withArguments(ListUtils.mapFirst(an.getArguments(), v -> {
+                        if (v instanceof J.Assignment &&
+                                ((J.Assignment) v).getVariable() instanceof J.Identifier &&
+                                "value".equals(((J.Identifier) ((J.Assignment) v).getVariable()).getSimpleName())) {
+                            Expression assignment = ((J.Assignment) v).getAssignment();
+                            if (assignment instanceof J.NewArray) {
+                                J.NewArray na = (J.NewArray) assignment;
+                                List<Expression> initializer = na.getInitializer();
+                                if (initializer != null && initializer.size() == 1 && !(initializer.get(0) instanceof J.Empty)) {
+                                    return initializer.get(0).withPrefix(Space.EMPTY);
+                                }
+                            }
+                            return assignment.withPrefix(Space.EMPTY);
+                        }
+                        return v;
+                    }));
+                }
+
+                return an;
+            }
+        };
+    }
+
+}