diff --git a/core-java-modules/core-java-optional/src/test/java/com/baeldung/optional/OptionalUnitTest.java b/core-java-modules/core-java-optional/src/test/java/com/baeldung/optional/OptionalUnitTest.java
index e5c4319bf7..de16e9b635 100644
--- a/core-java-modules/core-java-optional/src/test/java/com/baeldung/optional/OptionalUnitTest.java
+++ b/core-java-modules/core-java-optional/src/test/java/com/baeldung/optional/OptionalUnitTest.java
@@ -86,6 +86,15 @@ public class OptionalUnitTest {
         Optional<String> opt = Optional.ofNullable(null);
         String name = opt.get();
     }
+    
+    @Test
+    public void givenAnEmptyOptional_thenIsEmptyBehavesAsExpected() {
+        Optional<String> opt = Optional.of("Baeldung");
+        assertTrue(opt.isPresent());
+     
+        opt = Optional.ofNullable(null);
+        assertFalse(opt.isPresent());
+    }
 
     // Conditional Return With filter()
     @Test
diff --git a/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/app/Application.java b/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/app/Application.java
index f20fba737a..40f5341e29 100644
--- a/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/app/Application.java
+++ b/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/app/Application.java
@@ -1,43 +1,22 @@
 package com.baeldung.web.log.app;
 
-import javax.servlet.ServletContext;
-import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration;
 
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.EnableAutoConfiguration;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
 import org.springframework.context.annotation.ComponentScan;
-import org.springframework.web.context.ContextLoaderListener;
-import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
-import org.springframework.web.servlet.DispatcherServlet;
 import org.springframework.context.annotation.PropertySource;
 
 import com.baeldung.web.log.config.CustomeRequestLoggingFilter;
 
-import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;
-
 @EnableAutoConfiguration
 @ComponentScan("com.baeldung.web.log")
 @PropertySource("application-log.properties")
 @SpringBootApplication
-public class Application extends SpringBootServletInitializer {
+public class Application {
 
     public static void main(final String[] args) {
         SpringApplication.run(Application.class, args);
     }
-    
-    @Override
-    public void onStartup(ServletContext container) throws ServletException {
-
-        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
-        context.setConfigLocation("com.baeldung.web.log");
-        container.addListener(new ContextLoaderListener(context));
-
-        ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher", new DispatcherServlet(context));
-        dispatcher.setLoadOnStartup(1);
-        dispatcher.addMapping("/"); 
-
-        container.addFilter("customRequestLoggingFilter", CustomeRequestLoggingFilter.class).addMappingForServletNames(null, false, "dispatcher");
-    }
 }
\ No newline at end of file
diff --git a/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/config/CustomWebAppInitializer.java b/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/config/CustomWebAppInitializer.java
new file mode 100644
index 0000000000..f51bb52990
--- /dev/null
+++ b/spring-boot-modules/spring-boot-runtime/src/main/java/com/baeldung/web/log/config/CustomWebAppInitializer.java
@@ -0,0 +1,25 @@
+package com.baeldung.web.log.config;
+
+import javax.servlet.ServletContext;
+import javax.servlet.ServletException;
+import org.springframework.web.context.ContextLoaderListener;
+import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
+import org.springframework.web.servlet.DispatcherServlet;
+import org.springframework.web.WebApplicationInitializer;
+
+public class CustomWebAppInitializer implements WebApplicationInitializer {
+    
+    @Override
+    public void onStartup(ServletContext container) throws ServletException {
+
+        AnnotationConfigWebApplicationContext context = new AnnotationConfigWebApplicationContext();
+        context.setConfigLocation("com.baeldung.web.log");
+        container.addListener(new ContextLoaderListener(context));
+
+        ServletRegistration.Dynamic dispatcher = container.addServlet("dispatcher", new DispatcherServlet(context));
+        dispatcher.setLoadOnStartup(1);
+        dispatcher.addMapping("/"); 
+
+        container.addFilter("customRequestLoggingFilter", CustomeRequestLoggingFilter.class).addMappingForServletNames(null, false, "dispatcher");
+    }
+}
\ No newline at end of file
diff --git a/spring-core-2/src/main/java/com/baeldung/spring/config/MainWebAppInitializer.java b/spring-core-2/src/main/java/com/baeldung/spring/config/MyWebApplicationInitializer.java
similarity index 81%
rename from spring-core-2/src/main/java/com/baeldung/spring/config/MainWebAppInitializer.java
rename to spring-core-2/src/main/java/com/baeldung/spring/config/MyWebApplicationInitializer.java
index dd396a653f..034386ade9 100644
--- a/spring-core-2/src/main/java/com/baeldung/spring/config/MainWebAppInitializer.java
+++ b/spring-core-2/src/main/java/com/baeldung/spring/config/MyWebApplicationInitializer.java
@@ -6,15 +6,12 @@ import javax.servlet.ServletContext;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRegistration;
 
-import org.springframework.context.support.GenericApplicationContext;
 import org.springframework.web.WebApplicationInitializer;
 import org.springframework.web.context.ContextLoaderListener;
-import org.springframework.web.context.WebApplicationContext;
 import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
-import org.springframework.web.context.support.GenericWebApplicationContext;
 import org.springframework.web.servlet.DispatcherServlet;
 
-public class MainWebAppInitializer implements WebApplicationInitializer
+public class MyWebApplicationInitializer implements WebApplicationInitializer
 {
 
     /**
@@ -22,7 +19,7 @@ public class MainWebAppInitializer implements WebApplicationInitializer
      */
     @Override
     public void onStartup(final ServletContext sc) throws ServletException {
-        System.out.println("MainWebAppInitializer.onStartup()");
+        System.out.println("MyWebApplicationInitializer.onStartup()");
 
         // Create the 'root' Spring application context
         final AnnotationConfigWebApplicationContext root = new AnnotationConfigWebApplicationContext();
diff --git a/spring-core-2/src/test/java/com/baeldung/profiles/SpringProfilesWithMavenPropertiesIntegrationTest.java b/spring-core-2/src/test/java/com/baeldung/profiles/SpringProfilesWithMavenPropertiesIntegrationTest.java
index 60e9499d4b..1380e34ebd 100644
--- a/spring-core-2/src/test/java/com/baeldung/profiles/SpringProfilesWithMavenPropertiesIntegrationTest.java
+++ b/spring-core-2/src/test/java/com/baeldung/profiles/SpringProfilesWithMavenPropertiesIntegrationTest.java
@@ -16,7 +16,7 @@ public class SpringProfilesWithMavenPropertiesIntegrationTest {
     DatasourceConfig datasourceConfig;
 
     @Test
-    public void testSpringProfiles() {
+    public void setupDatasource() {
         Assert.assertTrue(datasourceConfig instanceof DevDatasourceConfig);
     }
 }
\ No newline at end of file
diff --git a/testing-modules/mockito/src/test/java/com/baeldung/mockito/MockitoAnnotationUnitTest.java b/testing-modules/mockito/src/test/java/com/baeldung/mockito/MockitoAnnotationUnitTest.java
index 731183bae2..27e3258efb 100644
--- a/testing-modules/mockito/src/test/java/com/baeldung/mockito/MockitoAnnotationUnitTest.java
+++ b/testing-modules/mockito/src/test/java/com/baeldung/mockito/MockitoAnnotationUnitTest.java
@@ -75,7 +75,53 @@ public class MockitoAnnotationUnitTest {
         Mockito.doReturn(100).when(spiedList).size();
         assertEquals(100, spiedList.size());
     }
+    
+    @Test
+    public void whenSpyingOnList_thenCorrect() {
+        List<String> list = new ArrayList<String>();
+        List<String> spyList = Mockito.spy(list);
+     
+        spyList.add("one");
+        spyList.add("two");
+     
+        Mockito.verify(spyList).add("one");
+        Mockito.verify(spyList).add("two");
+     
+        assertEquals(2, spyList.size());
+    }
 
+    @Test
+    public void whenUsingTheSpyAnnotation_thenObjectIsSpied() {
+        spiedList.add("one");
+        spiedList.add("two");
+     
+        Mockito.verify(spiedList).add("one");
+        Mockito.verify(spiedList).add("two");
+     
+        assertEquals(2, spiedList.size());
+    }
+    
+    @Test
+    public void whenStubASpy_thenStubbed() {
+        List<String> list = new ArrayList<String>();
+        List<String> spyList = Mockito.spy(list);
+     
+        assertEquals(0, spyList.size());
+     
+        Mockito.doReturn(100).when(spyList).size();
+        assertEquals(100, spyList.size());
+    }
+    
+    @Test
+    public void whenCreateSpy_thenCreate() {
+        List<String> spyList = Mockito.spy(new ArrayList<>());
+     
+        spyList.add("one");
+        Mockito.verify(spyList).add("one");
+     
+        assertEquals(1, spyList.size());
+    }
+    
     @Test
     public void whenNotUseCaptorAnnotation_thenCorrect() {
         final List<String> mockList = Mockito.mock(List.class);