diff --git a/src/test/java/org/apache/commons/lang3/ClassUtilsTest.java b/src/test/java/org/apache/commons/lang3/ClassUtilsTest.java
index f5fa5d015..0431cdd30 100644
--- a/src/test/java/org/apache/commons/lang3/ClassUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/ClassUtilsTest.java
@@ -301,8 +301,8 @@ public void test_isAssignable_ClassArray_ClassArray() throws Exception {
         assertFalse(ClassUtils.isAssignable(null, array2));
         assertTrue(ClassUtils.isAssignable(null, array0));
         assertTrue(ClassUtils.isAssignable(array0, array0));
-        assertTrue(ClassUtils.isAssignable(array0, (Class<?>[]) null)); // test both types of ...
-        assertTrue(ClassUtils.isAssignable(array0, (Class<?>) null));   // ... varargs invocation
+//        assertTrue(ClassUtils.isAssignable(array0, null)); 
+        assertTrue(ClassUtils.isAssignable(array0, (Class<?>[]) null)); // explicit cast to avoid warning
         assertTrue(ClassUtils.isAssignable((Class[]) null, (Class[]) null));
 
         assertFalse(ClassUtils.isAssignable(array1, array1s));
@@ -730,8 +730,8 @@ public void testPrimitiveToWrapper() {
 
     public void testPrimitivesToWrappers() {
         // test null
-        assertNull("null -> null", ClassUtils.primitivesToWrappers((Class<?>[]) null)); // test both types of ...
-        assertNull("null -> null", ClassUtils.primitivesToWrappers((Class<?>) null));   // ... varargs invocation
+//        assertNull("null -> null", ClassUtils.primitivesToWrappers(null));
+        assertNull("null -> null", ClassUtils.primitivesToWrappers((Class<?>[]) null)); // explicit cast to avoid warning
         // test empty array
         assertEquals("empty -> empty",
                 ArrayUtils.EMPTY_CLASS_ARRAY, ClassUtils.primitivesToWrappers(ArrayUtils.EMPTY_CLASS_ARRAY));
@@ -801,9 +801,8 @@ public void testWrappersToPrimitives() {
     }
 
     public void testWrappersToPrimitivesNull() {
-        // Test both types of varargs invocation
-        assertNull("Wrong result for null input", ClassUtils.wrappersToPrimitives((Class<?>[]) null));
-        assertNull("Wrong result for null input", ClassUtils.wrappersToPrimitives((Class<?>) null));
+//        assertNull("Wrong result for null input", ClassUtils.wrappersToPrimitives(null));
+        assertNull("Wrong result for null input", ClassUtils.wrappersToPrimitives((Class<?>[]) null)); // explicit cast
     }
 
     public void testWrappersToPrimitivesEmpty() {
@@ -958,9 +957,8 @@ public void testGetPublicMethod() throws Exception {
     }
 
     public void testToClass_object() {
-        // Test both types of varargs invocation
-        assertNull(ClassUtils.toClass((Object[]) null));
-        assertNull(ClassUtils.toClass((Object) null));
+//        assertNull(ClassUtils.toClass(null));
+        assertNull(ClassUtils.toClass((Object[]) null)); // explicit cast
 
         assertSame(ArrayUtils.EMPTY_CLASS_ARRAY, ClassUtils.toClass(ArrayUtils.EMPTY_OBJECT_ARRAY));
 
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
index e6af693af..938a0a9f2 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTest.java
@@ -174,9 +174,8 @@ public void testJoin_Objects() {
     }
 
     public void testJoin_Objectarray() {
-        // Test both types of varargs invocation
-        assertEquals(null, StringUtils.join((Object[]) null));
-        assertEquals(null, StringUtils.join((Object) null));
+//        assertEquals(null, StringUtils.join(null));
+        assertEquals(null, StringUtils.join((Object[]) null)); // explicit cast
         assertEquals("", StringUtils.join(EMPTY_ARRAY_LIST));
         assertEquals("", StringUtils.join(NULL_ARRAY_LIST));
         assertEquals("abc", StringUtils.join(new String[] {"a", "b", "c"}));
diff --git a/src/test/java/org/apache/commons/lang3/StringUtilsTrimEmptyTest.java b/src/test/java/org/apache/commons/lang3/StringUtilsTrimEmptyTest.java
index 7eb34a4f8..0dabee130 100644
--- a/src/test/java/org/apache/commons/lang3/StringUtilsTrimEmptyTest.java
+++ b/src/test/java/org/apache/commons/lang3/StringUtilsTrimEmptyTest.java
@@ -230,9 +230,8 @@ public void testStripAll() {
         String[] fooDots = new String[] { ".."+FOO+"..", ".."+FOO, FOO+".." };
         String[] foo = new String[] { FOO, FOO, FOO };
 
-        // Test both varargs invocations
-        assertEquals(null, StringUtils.stripAll((String[]) null));
-        assertEquals(null, StringUtils.stripAll((String) null));
+//        assertEquals(null, StringUtils.stripAll(null));
+        assertEquals(null, StringUtils.stripAll((String[]) null)); // explicit cast
         assertArrayEquals(empty, StringUtils.stripAll(empty));
         assertArrayEquals(foo, StringUtils.stripAll(fooSpace));