Reuse Suppliers.nul() in tests

Author: garydgregory

src/test/java/org/apache/commons/pool3/impl/TestGenericKeyedObjectPool.java

@@ -53,6 +53,7 @@
 import javax.management.ObjectName;
 
 import org.apache.commons.lang3.exception.ExceptionUtils;
+import org.apache.commons.lang3.function.Suppliers;
 import org.apache.commons.pool3.AbstractTestKeyedObjectPool;
 import org.apache.commons.pool3.BaseKeyedPooledObjectFactory;
 import org.apache.commons.pool3.DestroyMode;
@@ -2392,7 +2393,7 @@ void testNegativeMaxTotalPerKey() throws Exception {
     void testNPEOnFactoryNull() {
         // @formatter:off
         final DisconnectingWaiterFactory<String> factory = new DisconnectingWaiterFactory<>(
-            () -> null,  // Override default to always return null from makeObject
+            Suppliers.nul(),  // Override default to always return null from makeObject
             DisconnectingWaiterFactory.DEFAULT_DISCONNECTED_LIFECYCLE_ACTION,
             DisconnectingWaiterFactory.DEFAULT_DISCONNECTED_VALIDATION_ACTION
         );

src/test/java/org/apache/commons/pool3/impl/TestGenericObjectPool.java

@@ -52,6 +52,7 @@
 import javax.management.ObjectName;
 
 import org.apache.commons.lang3.ThreadUtils;
+import org.apache.commons.lang3.function.Suppliers;
 import org.apache.commons.lang3.time.DurationUtils;
 import org.apache.commons.pool3.BasePooledObjectFactory;
 import org.apache.commons.pool3.ObjectPool;
@@ -2653,7 +2654,7 @@ void testNoInvalidateNPE() throws Exception {
     @Timeout(value = 1000, unit = TimeUnit.MILLISECONDS)
     void testNPEOnFactoryNull() throws InterruptedException {
         final DisconnectingWaiterFactory<String> factory = new DisconnectingWaiterFactory<>(
-                () -> null, // Override default to always return null from makeObject
+                Suppliers.nul(), // Override default to always return null from makeObject
                 DisconnectingWaiterFactory.DEFAULT_DISCONNECTED_LIFECYCLE_ACTION,
                 DisconnectingWaiterFactory.DEFAULT_DISCONNECTED_VALIDATION_ACTION);
         try (GenericObjectPool<Waiter, IllegalStateException> pool = new GenericObjectPool<>(factory)) {