Fix ClassNotFoundException message variable (#1577)

* Fix ClassNotFoundException message variable

* Improve exception assertion in ClassUtilsTest

Update exception handling in assertGetClassThrowsException method to capture and verify exception messages.

* Fix indentation.

---------

Co-authored-by: Gary Gregory <garydgregory@users.noreply.github.com>

Author: eirv

src/main/java/org/apache/commons/lang3/ClassUtils.java

@@ -601,7 +601,7 @@ public static Class<?> getClass(final ClassLoader classLoader, final String clas
                 }
             }
         } while (lastDotIndex != -1);
-        throw new ClassNotFoundException(next);
+        throw new ClassNotFoundException(className);
     }
 
     /**

src/test/java/org/apache/commons/lang3/ClassUtilsTest.java

@@ -110,8 +110,11 @@ private void assertGetClassThrowsClassNotFound(final String className) {
     }
 
     private void assertGetClassThrowsException(final String className, final Class<? extends Exception> exceptionType) {
-        assertThrows(exceptionType, () -> ClassUtils.getClass(className),
+        final Exception exception = assertThrows(exceptionType, () -> ClassUtils.getClass(className),
             "ClassUtils.getClass() should fail with an exception of type " + exceptionType.getName() + " when given class name \"" + className + "\".");
+        if (className != null) {
+            assertEquals(className, exception.getMessage());
+        }
     }
 
     private void assertGetClassThrowsNullPointerException(final String className) {
@@ -1251,6 +1254,7 @@ void testGetClassClassNotFound() throws Exception {
         assertGetClassThrowsClassNotFound("bool");
         assertGetClassThrowsClassNotFound("bool[]");
         assertGetClassThrowsClassNotFound("integer[]");
+        assertGetClassThrowsClassNotFound("org.apache.commons.lang3.ClassUtilsTest.AClassThatCannotBeFound");
     }
 
     @Test