Clean up JUnit3 references

JUnit3 is not supported.

src/main/java/org/mockito/InjectMocks.java

@@ -149,7 +149,6 @@
  * <p>
  * <strong><code>MockitoAnnotations.openMocks(this)</code></strong> method has to be called to initialize annotated objects.
  * In above example, <code>openMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
- * For JUnit3 <code>openMocks()</code> can go to <code>setup()</code> method of a base class.
  * <strong>Instead</strong> you can also put openMocks() in your JUnit runner (&#064;RunWith) or use the built-in
  * {@link MockitoJUnitRunner}. Also, make sure to release any mocks after disposing your test class with a corresponding hook.
  * </p>

src/main/java/org/mockito/Mock.java

@@ -59,7 +59,6 @@
  * <p>
  * <strong><code>MockitoAnnotations.openMocks(this)</code></strong> method has to be called to initialize annotated objects.
  * In above example, <code>openMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
- * For JUnit3 <code>openMocks()</code> can go to <code>setup()</code> method of a base class.
  * <strong>Instead</strong> you can also put openMocks() in your JUnit runner (&#064;RunWith) or use the built-in
  * {@link MockitoJUnitRunner}. Also, make sure to release any mocks after disposing your test class with a corresponding hook.
  * </p>

src/main/java/org/mockito/MockitoAnnotations.java

@@ -56,7 +56,6 @@
  * <b><code>MockitoAnnotations.openMocks(this)</code></b> method has to be called to initialize annotated fields.
  * <p>
  * In above example, <code>openMocks()</code> is called in &#064;Before (JUnit4) method of test's base class.
- * For JUnit3 <code>openMocks()</code> can go to <code>setup()</code> method of a base class.
  * You can also put openMocks() in your JUnit runner (&#064;RunWith) or use built-in runner: {@link MockitoJUnitRunner}.
  * If static method mocks are used, it is required to close the initialization. Additionally, if using third-party
  * mock-makers, other life-cycles might be handled by the open-release routine.

src/main/java/org/mockito/internal/junit/ExceptionFactory.java

@@ -36,7 +36,7 @@ private static interface ExceptionFactoryImpl {
      * Returns an AssertionError that describes the fact that the arguments of an invocation are different.
      * If {@link org.opentest4j.AssertionFailedError} is on the class path (used by JUnit 5 and others),
      * it returns a class that extends it. Otherwise, if {@link junit.framework.ComparisonFailure} is on the
-     * class path (shipped with JUnit 3 and 4), it will return a class that extends that. This provides
+     * class path (shipped with JUnit 4), it will return a class that extends that. This provides
      * better IDE support as the comparison result can be opened in a visual diff. If neither are available,
      * it returns an instance of
      * {@link org.mockito.exceptions.verification.ArgumentsAreDifferent}.

src/test/java/org/mockito/internal/junit/ExceptionFactoryTest.java

@@ -15,42 +15,26 @@
 
 public class ExceptionFactoryTest {
 
-    private static ClassLoader classLoaderWithoutJUnitOrOpenTest =
+    private static final ClassLoader classLoaderWithoutJUnitOrOpenTest =
             excludingClassLoader()
                     .withCodeSourceUrlOf(ExceptionFactory.class)
                     .without("org.junit", "junit", "org.opentest4j")
                     .build();
-    private static ClassLoader classLoaderWithoutOpenTest =
-            excludingClassLoader()
-                    .withCodeSourceUrlOf(ExceptionFactory.class, org.junit.ComparisonFailure.class)
-                    .without("org.opentest4j")
-                    .build();
-    private static ClassLoader currentClassLoader = ExceptionFactoryTest.class.getClassLoader();
+    private static final ClassLoader currentClassLoader =
+            ExceptionFactoryTest.class.getClassLoader();
 
     /** loaded by the current classloader */
     private static Class<?> opentestComparisonFailure;
 
     private static Class<?> opentestArgumentsAreDifferent;
 
-    /** loaded by the classloader {@value #classLoaderWithoutOpenTest}, which excludes OpenTest4J classes */
-    private static Class<?> junit3ComparisonFailure;
-
-    private static Class<?> junit3ArgumentsAreDifferent;
-
     /** loaded by the custom classloader {@value #classLoaderWithoutJUnitOrOpenTest}, which excludes JUnit and OpenTest4J classes */
     private static Class<?> nonJunitArgumentsAreDifferent;
 
     @BeforeClass
     public static void init() throws ClassNotFoundException {
         nonJunitArgumentsAreDifferent =
                 classLoaderWithoutJUnitOrOpenTest.loadClass(ArgumentsAreDifferent.class.getName());
-        junit3ComparisonFailure =
-                classLoaderWithoutOpenTest.loadClass(
-                        junit.framework.ComparisonFailure.class.getName());
-        junit3ArgumentsAreDifferent =
-                classLoaderWithoutOpenTest.loadClass(
-                        org.mockito.exceptions.verification.junit.ArgumentsAreDifferent.class
-                                .getName());
         opentestComparisonFailure = org.opentest4j.AssertionFailedError.class;
         opentestArgumentsAreDifferent =
                 org.mockito.exceptions.verification.opentest4j.ArgumentsAreDifferent.class;
@@ -63,15 +47,6 @@ public void createArgumentsAreDifferentException_withoutJUnitOrOpenTest() throws
         assertThat(e).isExactlyInstanceOf(nonJunitArgumentsAreDifferent);
     }
 
-    @Test
-    public void createArgumentsAreDifferentException_withJUnit3_butNotOpenTest() throws Exception {
-        AssertionError e = invokeFactoryThroughLoader(classLoaderWithoutOpenTest);
-
-        assertThat(e)
-                .isExactlyInstanceOf(junit3ArgumentsAreDifferent)
-                .isInstanceOf(junit3ComparisonFailure);
-    }
-
     @Test
     public void createArgumentsAreDifferentException_withOpenTest() throws Exception {
         AssertionError e = invokeFactoryThroughLoader(currentClassLoader);
@@ -92,17 +67,6 @@ public void createArgumentsAreDifferentException_withoutJUnitOrOpenTest_2x() thr
         assertThat(e).isExactlyInstanceOf(nonJunitArgumentsAreDifferent);
     }
 
-    @Test
-    public void createArgumentsAreDifferentException_withJUnit3_2x() throws Exception {
-        AssertionError e;
-
-        e = invokeFactoryThroughLoader(classLoaderWithoutOpenTest);
-        assertThat(e).isExactlyInstanceOf(junit3ArgumentsAreDifferent);
-
-        e = invokeFactoryThroughLoader(classLoaderWithoutOpenTest);
-        assertThat(e).isExactlyInstanceOf(junit3ArgumentsAreDifferent);
-    }
-
     @Test
     public void createArgumentsAreDifferentException_withOpenTest_2x() throws Exception {
         AssertionError e;