diff --git a/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java b/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java
index 7db0abfce..440e47552 100644
--- a/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java
+++ b/async-method-invocation/src/test/java/com/iluwatar/async/method/invocation/ThreadAsyncExecutorTest.java
@@ -30,272 +30,287 @@ import static org.mockito.internal.verification.VerificationModeFactory.times;
  */
 public class ThreadAsyncExecutorTest {
 
-	/**
-	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
-	 */
-	@Test(timeout = 3000)
-	public void testSuccessfulTaskWithoutCallback() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+  /**
+   * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
+   */
+  @Test(timeout = 3000)
+  public void testSuccessfulTaskWithoutCallback() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
 
-		final Object result = new Object();
-		final Callable<Object> task = mock(Callable.class);
-		when(task.call()).thenReturn(result);
+    final Object result = new Object();
+    final Callable<Object> task = mock(Callable.class);
+    when(task.call()).thenReturn(result);
 
-		final AsyncResult<Object> asyncResult = executor.startProcess(task);
-		assertNotNull(asyncResult);
-		asyncResult.await(); // Prevent timing issues, and wait until the result is available
-		assertTrue(asyncResult.isCompleted());
+    final AsyncResult<Object> asyncResult = executor.startProcess(task);
+    assertNotNull(asyncResult);
+    asyncResult.await(); // Prevent timing issues, and wait until the result is available
+    assertTrue(asyncResult.isCompleted());
 
-		// Our task should only execute once ...
-		verify(task, times(1)).call();
+    // Our task should only execute once ...
+    verify(task, times(1)).call();
 
-		// ... and the result should be exactly the same object
-		assertSame(result, asyncResult.getValue());
-	}
+    // ... and the result should be exactly the same object
+    assertSame(result, asyncResult.getValue());
+  }
 
-	/**
-	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
-	 */
-	@Test(timeout = 3000)
-	public void testSuccessfulTaskWithCallback() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+  /**
+   * Test used to verify the happy path of
+   * {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
+   */
+  @Test(timeout = 3000)
+  public void testSuccessfulTaskWithCallback() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
 
-		final Object result = new Object();
-		final Callable<Object> task = mock(Callable.class);
-		when(task.call()).thenReturn(result);
+    final Object result = new Object();
+    final Callable<Object> task = mock(Callable.class);
+    when(task.call()).thenReturn(result);
 
-		final AsyncCallback callback = mock(AsyncCallback.class);
-		final AsyncResult<Object> asyncResult = executor.startProcess(task, callback);
-		assertNotNull(asyncResult);
-		asyncResult.await(); // Prevent timing issues, and wait until the result is available
-		assertTrue(asyncResult.isCompleted());
+    final AsyncCallback callback = mock(AsyncCallback.class);
+    final AsyncResult<Object> asyncResult = executor.startProcess(task, callback);
+    assertNotNull(asyncResult);
+    asyncResult.await(); // Prevent timing issues, and wait until the result is available
+    assertTrue(asyncResult.isCompleted());
 
-		// Our task should only execute once ...
-		verify(task, times(1)).call();
+    // Our task should only execute once ...
+    verify(task, times(1)).call();
 
-		// ... same for the callback, we expect our object
-		final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor.forClass((Class) Optional.class);
-		verify(callback, times(1)).onComplete(eq(result), optionalCaptor.capture());
+    // ... same for the callback, we expect our object
+    final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor
+        .forClass((Class) Optional.class);
+    verify(callback, times(1)).onComplete(eq(result), optionalCaptor.capture());
 
-		final Optional<Exception> optionalException = optionalCaptor.getValue();
-		assertNotNull(optionalException);
-		assertFalse(optionalException.isPresent());
+    final Optional<Exception> optionalException = optionalCaptor.getValue();
+    assertNotNull(optionalException);
+    assertFalse(optionalException.isPresent());
 
-		// ... and the result should be exactly the same object
-		assertSame(result, asyncResult.getValue());
-	}
+    // ... and the result should be exactly the same object
+    assertSame(result, asyncResult.getValue());
+  }
 
-	/**
-	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
-	 * when a task takes a while to execute
-	 */
-	@Test(timeout = 5000)
-	public void testLongRunningTaskWithoutCallback() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+  /**
+   * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)} when a
+   * task takes a while to execute
+   */
+  @Test(timeout = 5000)
+  public void testLongRunningTaskWithoutCallback() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
 
-		final Object result = new Object();
-		final Callable<Object> task = mock(Callable.class);
-		when(task.call()).thenAnswer(i -> {
-			Thread.sleep(1500);
-			return result;
-		});
+    final Object result = new Object();
+    final Callable<Object> task = mock(Callable.class);
+    when(task.call()).thenAnswer(i -> {
+      Thread.sleep(1500);
+      return result;
+    });
 
-		final AsyncResult<Object> asyncResult = executor.startProcess(task);
-		assertNotNull(asyncResult);
-		assertFalse(asyncResult.isCompleted());
+    final AsyncResult<Object> asyncResult = executor.startProcess(task);
+    assertNotNull(asyncResult);
+    assertFalse(asyncResult.isCompleted());
 
-		try {
-			asyncResult.getValue();
-			fail("Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
-		} catch (IllegalStateException e) {
-			assertNotNull(e.getMessage());
-		}
+    try {
+      asyncResult.getValue();
+      fail(
+          "Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
+    } catch (IllegalStateException e) {
+      assertNotNull(e.getMessage());
+    }
 
-		// Our task should only execute once, but it can take a while ...
-		verify(task, timeout(3000).times(1)).call();
+    // Our task should only execute once, but it can take a while ...
+    verify(task, timeout(3000).times(1)).call();
 
-		// Prevent timing issues, and wait until the result is available
-		asyncResult.await();
-		assertTrue(asyncResult.isCompleted());
-		verifyNoMoreInteractions(task);
+    // Prevent timing issues, and wait until the result is available
+    asyncResult.await();
+    assertTrue(asyncResult.isCompleted());
+    verifyNoMoreInteractions(task);
 
-		// ... and the result should be exactly the same object
-		assertSame(result, asyncResult.getValue());
-	}
+    // ... and the result should be exactly the same object
+    assertSame(result, asyncResult.getValue());
+  }
 
-	/**
-	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
-	 * when a task takes a while to execute
-	 */
-	@Test(timeout = 5000)
-	public void testLongRunningTaskWithCallback() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+  /**
+   * Test used to verify the happy path of
+   * {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)} when a task takes a while to
+   * execute
+   */
+  @Test(timeout = 5000)
+  public void testLongRunningTaskWithCallback() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
 
-		final Object result = new Object();
-		final Callable<Object> task = mock(Callable.class);
-		when(task.call()).thenAnswer(i -> {
-			Thread.sleep(1500);
-			return result;
-		});
+    final Object result = new Object();
+    final Callable<Object> task = mock(Callable.class);
+    when(task.call()).thenAnswer(i -> {
+      Thread.sleep(1500);
+      return result;
+    });
 
-		final AsyncCallback<Object> callback = mock(AsyncCallback.class);
-		final AsyncResult<Object> asyncResult = executor.startProcess(task, callback);
-		assertNotNull(asyncResult);
-		assertFalse(asyncResult.isCompleted());
+    final AsyncCallback<Object> callback = mock(AsyncCallback.class);
+    final AsyncResult<Object> asyncResult = executor.startProcess(task, callback);
+    assertNotNull(asyncResult);
+    assertFalse(asyncResult.isCompleted());
 
-		verifyZeroInteractions(callback);
+    verifyZeroInteractions(callback);
 
-		try {
-			asyncResult.getValue();
-			fail("Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
-		} catch (IllegalStateException e) {
-			assertNotNull(e.getMessage());
-		}
+    try {
+      asyncResult.getValue();
+      fail(
+          "Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
+    } catch (IllegalStateException e) {
+      assertNotNull(e.getMessage());
+    }
 
-		// Our task should only execute once, but it can take a while ...
-		verify(task, timeout(3000).times(1)).call();
+    // Our task should only execute once, but it can take a while ...
+    verify(task, timeout(3000).times(1)).call();
 
-		final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor.forClass((Class) Optional.class);
-		verify(callback, timeout(3000).times(1)).onComplete(eq(result), optionalCaptor.capture());
+    final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor
+        .forClass((Class) Optional.class);
+    verify(callback, timeout(3000).times(1)).onComplete(eq(result), optionalCaptor.capture());
 
-		final Optional<Exception> optionalException = optionalCaptor.getValue();
-		assertNotNull(optionalException);
-		assertFalse(optionalException.isPresent());
+    final Optional<Exception> optionalException = optionalCaptor.getValue();
+    assertNotNull(optionalException);
+    assertFalse(optionalException.isPresent());
 
-		// Prevent timing issues, and wait until the result is available
-		asyncResult.await();
-		assertTrue(asyncResult.isCompleted());
-		verifyNoMoreInteractions(task, callback);
+    // Prevent timing issues, and wait until the result is available
+    asyncResult.await();
+    assertTrue(asyncResult.isCompleted());
+    verifyNoMoreInteractions(task, callback);
 
-		// ... and the result should be exactly the same object
-		assertSame(result, asyncResult.getValue());
-	}
+    // ... and the result should be exactly the same object
+    assertSame(result, asyncResult.getValue());
+  }
 
-	/**
-	 * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)}
-	 * when a task takes a while to execute, while waiting on the result using {@link ThreadAsyncExecutor#endProcess(AsyncResult)}
-	 */
-	@Test(timeout = 5000)
-	public void testEndProcess() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+  /**
+   * Test used to verify the happy path of {@link ThreadAsyncExecutor#startProcess(Callable)} when a
+   * task takes a while to execute, while waiting on the result using
+   * {@link ThreadAsyncExecutor#endProcess(AsyncResult)}
+   */
+  @Test(timeout = 5000)
+  public void testEndProcess() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
 
-		final Object result = new Object();
-		final Callable<Object> task = mock(Callable.class);
-		when(task.call()).thenAnswer(i -> {
-			Thread.sleep(1500);
-			return result;
-		});
+    final Object result = new Object();
+    final Callable<Object> task = mock(Callable.class);
+    when(task.call()).thenAnswer(i -> {
+      Thread.sleep(1500);
+      return result;
+    });
 
-		final AsyncResult<Object> asyncResult = executor.startProcess(task);
-		assertNotNull(asyncResult);
-		assertFalse(asyncResult.isCompleted());
+    final AsyncResult<Object> asyncResult = executor.startProcess(task);
+    assertNotNull(asyncResult);
+    assertFalse(asyncResult.isCompleted());
 
-		try {
-			asyncResult.getValue();
-			fail("Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
-		} catch (IllegalStateException e) {
-			assertNotNull(e.getMessage());
-		}
+    try {
+      asyncResult.getValue();
+      fail(
+          "Expected IllegalStateException when calling AsyncResult#getValue on a non-completed task");
+    } catch (IllegalStateException e) {
+      assertNotNull(e.getMessage());
+    }
 
-		assertSame(result, executor.endProcess(asyncResult));
-		verify(task, times(1)).call();
-		assertTrue(asyncResult.isCompleted());
+    assertSame(result, executor.endProcess(asyncResult));
+    verify(task, times(1)).call();
+    assertTrue(asyncResult.isCompleted());
 
-		// Calling end process a second time while already finished should give the same result
-		assertSame(result, executor.endProcess(asyncResult));
-		verifyNoMoreInteractions(task);
-	}
+    // Calling end process a second time while already finished should give the same result
+    assertSame(result, executor.endProcess(asyncResult));
+    verifyNoMoreInteractions(task);
+  }
 
-	/**
-	 * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable)}
-	 * when the callable is 'null'
-	 */
-	@Test(timeout = 3000)
-	public void testNullTask() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
-		final AsyncResult<Object> asyncResult = executor.startProcess(null);
+  /**
+   * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable)} when
+   * the callable is 'null'
+   */
+  @Test(timeout = 3000)
+  public void testNullTask() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+    final AsyncResult<Object> asyncResult = executor.startProcess(null);
 
-		assertNotNull("The AsyncResult should not be 'null', even though the task was 'null'.", asyncResult);
-		asyncResult.await(); // Prevent timing issues, and wait until the result is available
-		assertTrue(asyncResult.isCompleted());
+    assertNotNull("The AsyncResult should not be 'null', even though the task was 'null'.",
+        asyncResult);
+    asyncResult.await(); // Prevent timing issues, and wait until the result is available
+    assertTrue(asyncResult.isCompleted());
 
-		try {
-			asyncResult.getValue();
-			fail("Expected ExecutionException with NPE as cause");
-		} catch (final ExecutionException e) {
-			assertNotNull(e.getMessage());
-			assertNotNull(e.getCause());
-			assertEquals(NullPointerException.class, e.getCause().getClass());
-		}
+    try {
+      asyncResult.getValue();
+      fail("Expected ExecutionException with NPE as cause");
+    } catch (final ExecutionException e) {
+      assertNotNull(e.getMessage());
+      assertNotNull(e.getCause());
+      assertEquals(NullPointerException.class, e.getCause().getClass());
+    }
 
-	}
+  }
 
-	/**
-	 * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
-	 * when the callable is 'null', but the asynchronous callback is provided
-	 */
-	@Test(timeout = 3000)
-	public void testNullTaskWithCallback() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
-		final AsyncCallback<Object> callback = mock(AsyncCallback.class);
-		final AsyncResult<Object> asyncResult = executor.startProcess(null, callback);
+  /**
+   * Test used to verify the behaviour of
+   * {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)} when the callable is 'null',
+   * but the asynchronous callback is provided
+   */
+  @Test(timeout = 3000)
+  public void testNullTaskWithCallback() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+    final AsyncCallback<Object> callback = mock(AsyncCallback.class);
+    final AsyncResult<Object> asyncResult = executor.startProcess(null, callback);
 
-		assertNotNull("The AsyncResult should not be 'null', even though the task was 'null'.", asyncResult);
-		asyncResult.await(); // Prevent timing issues, and wait until the result is available
-		assertTrue(asyncResult.isCompleted());
+    assertNotNull("The AsyncResult should not be 'null', even though the task was 'null'.",
+        asyncResult);
+    asyncResult.await(); // Prevent timing issues, and wait until the result is available
+    assertTrue(asyncResult.isCompleted());
 
-		final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor.forClass((Class) Optional.class);
-		verify(callback, times(1)).onComplete(Matchers.isNull(), optionalCaptor.capture());
+    final ArgumentCaptor<Optional<Exception>> optionalCaptor = ArgumentCaptor
+        .forClass((Class) Optional.class);
+    verify(callback, times(1)).onComplete(Matchers.isNull(), optionalCaptor.capture());
 
-		final Optional<Exception> optionalException = optionalCaptor.getValue();
-		assertNotNull(optionalException);
-		assertTrue(optionalException.isPresent());
+    final Optional<Exception> optionalException = optionalCaptor.getValue();
+    assertNotNull(optionalException);
+    assertTrue(optionalException.isPresent());
 
-		final Exception exception = optionalException.get();
-		assertNotNull(exception);
-		assertEquals(NullPointerException.class, exception.getClass());
+    final Exception exception = optionalException.get();
+    assertNotNull(exception);
+    assertEquals(NullPointerException.class, exception.getClass());
 
-		try {
-			asyncResult.getValue();
-			fail("Expected ExecutionException with NPE as cause");
-		} catch (final ExecutionException e) {
-			assertNotNull(e.getMessage());
-			assertNotNull(e.getCause());
-			assertEquals(NullPointerException.class, e.getCause().getClass());
-		}
+    try {
+      asyncResult.getValue();
+      fail("Expected ExecutionException with NPE as cause");
+    } catch (final ExecutionException e) {
+      assertNotNull(e.getMessage());
+      assertNotNull(e.getCause());
+      assertEquals(NullPointerException.class, e.getCause().getClass());
+    }
 
-	}
+  }
 
-	/**
-	 * Test used to verify the behaviour of {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)}
-	 * when both the callable and the asynchronous callback are 'null'
-	 */
-	@Test(timeout = 3000)
-	public void testNullTaskWithNullCallback() throws Exception {
-		// Instantiate a new executor and start a new 'null' task ...
-		final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
-		final AsyncResult<Object> asyncResult = executor.startProcess(null, null);
+  /**
+   * Test used to verify the behaviour of
+   * {@link ThreadAsyncExecutor#startProcess(Callable, AsyncCallback)} when both the callable and
+   * the asynchronous callback are 'null'
+   */
+  @Test(timeout = 3000)
+  public void testNullTaskWithNullCallback() throws Exception {
+    // Instantiate a new executor and start a new 'null' task ...
+    final ThreadAsyncExecutor executor = new ThreadAsyncExecutor();
+    final AsyncResult<Object> asyncResult = executor.startProcess(null, null);
 
-		assertNotNull("The AsyncResult should not be 'null', even though the task and callback were 'null'.", asyncResult);
-		asyncResult.await(); // Prevent timing issues, and wait until the result is available
-		assertTrue(asyncResult.isCompleted());
+    assertNotNull(
+        "The AsyncResult should not be 'null', even though the task and callback were 'null'.",
+        asyncResult);
+    asyncResult.await(); // Prevent timing issues, and wait until the result is available
+    assertTrue(asyncResult.isCompleted());
 
-		try {
-			asyncResult.getValue();
-			fail("Expected ExecutionException with NPE as cause");
-		} catch (final ExecutionException e) {
-			assertNotNull(e.getMessage());
-			assertNotNull(e.getCause());
-			assertEquals(NullPointerException.class, e.getCause().getClass());
-		}
+    try {
+      asyncResult.getValue();
+      fail("Expected ExecutionException with NPE as cause");
+    } catch (final ExecutionException e) {
+      assertNotNull(e.getMessage());
+      assertNotNull(e.getCause());
+      assertEquals(NullPointerException.class, e.getCause().getClass());
+    }
 
-	}
+  }
 
 }
\ No newline at end of file