diff --git a/spring-test/src/test/java/org/springframework/mock/web/MockFilterChainTests.java b/spring-test/src/test/java/org/springframework/mock/web/MockFilterChainTests.java
index 5b0f4bf4edffb64d70a0cc1911ffe38ebe9e4b70..4babe4467a327fd7ddc4e810b3c49d682c89a498 100644
--- a/spring-test/src/test/java/org/springframework/mock/web/MockFilterChainTests.java
+++ b/spring-test/src/test/java/org/springframework/mock/web/MockFilterChainTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -55,7 +55,7 @@ class MockFilterChainTests {
 	@Test
 	void constructorNullServlet() {
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				new MockFilterChain((Servlet) null));
+				new MockFilterChain(null));
 	}
 
 	@Test
diff --git a/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java b/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java
index ed837c9267c5a74da1061f999f108137f3d10b11..6ade7c90a710cc4407ee2e4a80745d0e883c1506 100644
--- a/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java
+++ b/spring-test/src/test/java/org/springframework/mock/web/MockHttpServletRequestTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,6 +19,7 @@ package org.springframework.mock.web;
 import java.io.IOException;
 import java.net.URL;
 import java.nio.charset.Charset;
+import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -112,7 +113,7 @@ class MockHttpServletRequestTests {
 	@Test
 	void setContentAndGetContentAsStringWithExplicitCharacterEncoding() throws IOException {
 		String palindrome = "ablE was I ere I saw Elba";
-		byte[] bytes = palindrome.getBytes("UTF-16");
+		byte[] bytes = palindrome.getBytes(StandardCharsets.UTF_16);
 		request.setCharacterEncoding("UTF-16");
 		request.setContent(bytes);
 		assertThat(request.getContentLength()).isEqualTo(bytes.length);
@@ -394,7 +395,7 @@ class MockHttpServletRequestTests {
 	void getServerNameWithInvalidIpv6AddressViaHostHeader() {
 		request.addHeader(HOST, "[::ffff:abcd:abcd"); // missing closing bracket
 		assertThatIllegalStateException()
-			.isThrownBy(() -> request.getServerName())
+			.isThrownBy(request::getServerName)
 			.withMessageStartingWith("Invalid Host header: ");
 	}
 
@@ -426,7 +427,7 @@ class MockHttpServletRequestTests {
 	void getServerPortWithInvalidIpv6AddressViaHostHeader() {
 		request.addHeader(HOST, "[::ffff:abcd:abcd:8080"); // missing closing bracket
 		assertThatIllegalStateException()
-			.isThrownBy(() -> request.getServerPort())
+			.isThrownBy(request::getServerPort)
 			.withMessageStartingWith("Invalid Host header: ");
 	}
 
@@ -434,7 +435,7 @@ class MockHttpServletRequestTests {
 	void getServerPortWithIpv6AddressAndInvalidPortViaHostHeader() {
 		request.addHeader(HOST, "[::ffff:abcd:abcd]:bogus"); // "bogus" is not a port number
 		assertThatExceptionOfType(NumberFormatException.class)
-			.isThrownBy(() -> request.getServerPort())
+			.isThrownBy(request::getServerPort)
 			.withMessageContaining("bogus");
 	}
 
@@ -521,7 +522,7 @@ class MockHttpServletRequestTests {
 	void getRequestURLWithInvalidIpv6AddressViaHostHeader() {
 		request.addHeader(HOST, "[::ffff:abcd:abcd"); // missing closing bracket
 		assertThatIllegalStateException()
-			.isThrownBy(() -> request.getRequestURL())
+			.isThrownBy(request::getRequestURL)
 			.withMessageStartingWith("Invalid Host header: ");
 	}
 
diff --git a/spring-test/src/test/java/org/springframework/test/web/servlet/setup/StandaloneMockMvcBuilderTests.java b/spring-test/src/test/java/org/springframework/test/web/servlet/setup/StandaloneMockMvcBuilderTests.java
index 7c31562e7c5e8327dc2ce3a2f464d2aecd6633da..d55800e1817b96805e906243881117da6aeb731a 100644
--- a/spring-test/src/test/java/org/springframework/test/web/servlet/setup/StandaloneMockMvcBuilderTests.java
+++ b/spring-test/src/test/java/org/springframework/test/web/servlet/setup/StandaloneMockMvcBuilderTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -49,10 +49,10 @@ import static org.assertj.core.api.Assertions.assertThatIllegalArgumentException
  * @author Rob Winch
  * @author Sebastien Deleuze
  */
-public class StandaloneMockMvcBuilderTests {
+class StandaloneMockMvcBuilderTests {
 
 	@Test  // SPR-10825
-	public void placeHoldersInRequestMapping() throws Exception {
+	void placeHoldersInRequestMapping() throws Exception {
 		TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PlaceholderController());
 		builder.addPlaceholderValue("sys.login.ajax", "/foo");
 		builder.build();
@@ -68,7 +68,7 @@ public class StandaloneMockMvcBuilderTests {
 
 	@Test  // SPR-13637
 	@SuppressWarnings("deprecation")
-	public void suffixPatternMatch() throws Exception {
+	void suffixPatternMatch() throws Exception {
 		TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PersonController());
 		builder.setUseSuffixPatternMatch(false);
 		builder.build();
@@ -86,7 +86,7 @@ public class StandaloneMockMvcBuilderTests {
 	}
 
 	@Test  // SPR-12553
-	public void applicationContextAttribute() {
+	void applicationContextAttribute() {
 		TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PlaceholderController());
 		builder.addPlaceholderValue("sys.login.ajax", "/foo");
 		WebApplicationContext  wac = builder.initWebAppContext();
@@ -94,28 +94,28 @@ public class StandaloneMockMvcBuilderTests {
 	}
 
 	@Test
-	public void addFiltersFiltersNull() {
+	void addFiltersFiltersNull() {
 		StandaloneMockMvcBuilder builder = MockMvcBuilders.standaloneSetup(new PersonController());
 		assertThatIllegalArgumentException().isThrownBy(() ->
 				builder.addFilters((Filter[]) null));
 	}
 
 	@Test
-	public void addFiltersFiltersContainsNull() {
+	void addFiltersFiltersContainsNull() {
 		StandaloneMockMvcBuilder builder = MockMvcBuilders.standaloneSetup(new PersonController());
 		assertThatIllegalArgumentException().isThrownBy(() ->
-				builder.addFilters(new ContinueFilter(), (Filter) null));
+				builder.addFilters(new ContinueFilter(), null));
 	}
 
 	@Test
-	public void addFilterPatternsNull() {
+	void addFilterPatternsNull() {
 		StandaloneMockMvcBuilder builder = MockMvcBuilders.standaloneSetup(new PersonController());
 		assertThatIllegalArgumentException().isThrownBy(() ->
 				builder.addFilter(new ContinueFilter(), (String[]) null));
 	}
 
 	@Test
-	public void addFilterPatternContainsNull() {
+	void addFilterPatternContainsNull() {
 		StandaloneMockMvcBuilder builder = MockMvcBuilders.standaloneSetup(new PersonController());
 		assertThatIllegalArgumentException().isThrownBy(() ->
 				builder.addFilter(new ContinueFilter(), (String) null));
@@ -123,7 +123,7 @@ public class StandaloneMockMvcBuilderTests {
 
 	@Test  // SPR-13375
 	@SuppressWarnings("rawtypes")
-	public void springHandlerInstantiator() {
+	void springHandlerInstantiator() {
 		TestStandaloneMockMvcBuilder builder = new TestStandaloneMockMvcBuilder(new PersonController());
 		builder.build();
 		SpringHandlerInstantiator instantiator = new SpringHandlerInstantiator(builder.wac.getAutowireCapableBeanFactory());
@@ -171,7 +171,7 @@ public class StandaloneMockMvcBuilderTests {
 	}
 
 
-	private class ContinueFilter extends OncePerRequestFilter {
+	private static class ContinueFilter extends OncePerRequestFilter {
 
 		@Override
 		protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response,