diff --git a/spring-web/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTests.java b/spring-web/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTests.java
index 3156b8b3476..a36cd55a62d 100644
--- a/spring-web/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTests.java
+++ b/spring-web/src/test/java/org/springframework/web/filter/ShallowEtagHeaderFilterTests.java
@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -17,32 +17,33 @@
 package org.springframework.web.filter;
 
 import java.io.InputStream;
-import java.nio.charset.StandardCharsets;
 
 import jakarta.servlet.FilterChain;
 import jakarta.servlet.http.HttpServletResponse;
 import org.junit.jupiter.api.Test;
 
-import org.springframework.http.MediaType;
 import org.springframework.util.FileCopyUtils;
 import org.springframework.web.testfixture.servlet.MockHttpServletRequest;
 import org.springframework.web.testfixture.servlet.MockHttpServletResponse;
 
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.springframework.http.MediaType.TEXT_PLAIN_VALUE;
 
 /**
  * Tests for {@link ShallowEtagHeaderFilter}.
+ *
  * @author Arjen Poutsma
  * @author Brian Clozel
  * @author Juergen Hoeller
  */
-public class ShallowEtagHeaderFilterTests {
+class ShallowEtagHeaderFilterTests {
 
 	private final ShallowEtagHeaderFilter filter = new ShallowEtagHeaderFilter();
 
 
 	@Test
-	public void isEligibleForEtag() {
+	void isEligibleForEtag() {
 		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
@@ -61,15 +62,15 @@ public class ShallowEtagHeaderFilterTests {
 	}
 
 	@Test
-	public void filterNoMatch() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterNoMatch() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK);
-			filterResponse.setContentType(MediaType.TEXT_PLAIN_VALUE);
+			filterResponse.setContentType(TEXT_PLAIN_VALUE);
 			FileCopyUtils.copy(responseBody, filterResponse.getOutputStream());
 		};
 		filter.doFilter(request, response, filterChain);
@@ -77,21 +78,21 @@ public class ShallowEtagHeaderFilterTests {
 		assertThat(response.getStatus()).as("Invalid status").isEqualTo(200);
 		assertThat(response.getHeader("ETag")).as("Invalid ETag").isEqualTo("\"0b10a8db164e0754105b7a99be72e3fe5\"");
 		assertThat(response.getContentLength()).as("Invalid Content-Length header").isGreaterThan(0);
-		assertThat(response.getContentType()).as("Invalid Content-Type header").isEqualTo(MediaType.TEXT_PLAIN_VALUE);
+		assertThat(response.getContentType()).as("Invalid Content-Type header").isEqualTo(TEXT_PLAIN_VALUE);
 		assertThat(response.getContentAsByteArray()).as("Invalid content").isEqualTo(responseBody);
 	}
 
 	@Test
-	public void filterNoMatchWeakETag() throws Exception {
+	void filterNoMatchWeakETag() throws Exception {
 		this.filter.setWriteWeakETag(true);
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK);
-			filterResponse.setContentType(MediaType.TEXT_PLAIN_VALUE);
+			filterResponse.setContentType(TEXT_PLAIN_VALUE);
 			FileCopyUtils.copy(responseBody, filterResponse.getOutputStream());
 		};
 		filter.doFilter(request, response, filterChain);
@@ -99,22 +100,22 @@ public class ShallowEtagHeaderFilterTests {
 		assertThat(response.getStatus()).as("Invalid status").isEqualTo(200);
 		assertThat(response.getHeader("ETag")).as("Invalid ETag").isEqualTo("W/\"0b10a8db164e0754105b7a99be72e3fe5\"");
 		assertThat(response.getContentLength()).as("Invalid Content-Length header").isGreaterThan(0);
-		assertThat(response.getContentType()).as("Invalid Content-Type header").isEqualTo(MediaType.TEXT_PLAIN_VALUE);
+		assertThat(response.getContentType()).as("Invalid Content-Type header").isEqualTo(TEXT_PLAIN_VALUE);
 		assertThat(response.getContentAsByteArray()).as("Invalid content").isEqualTo(responseBody);
 	}
 
 	@Test
-	public void filterMatch() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterMatch() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		String etag = "\"0b10a8db164e0754105b7a99be72e3fe5\"";
 		request.addHeader("If-None-Match", etag);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
-			byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+			byte[] responseBody = "Hello World".getBytes(UTF_8);
 			filterResponse.setContentLength(responseBody.length);
-			filterResponse.setContentType(MediaType.TEXT_PLAIN_VALUE);
+			filterResponse.setContentType(TEXT_PLAIN_VALUE);
 			FileCopyUtils.copy(responseBody, filterResponse.getOutputStream());
 		};
 		filter.doFilter(request, response, filterChain);
@@ -123,20 +124,19 @@ public class ShallowEtagHeaderFilterTests {
 		assertThat(response.getHeader("ETag")).as("Invalid ETag").isEqualTo("\"0b10a8db164e0754105b7a99be72e3fe5\"");
 		assertThat(response.containsHeader("Content-Length")).as("Response has Content-Length header").isFalse();
 		assertThat(response.containsHeader("Content-Type")).as("Response has Content-Type header").isFalse();
-		byte[] expecteds = new byte[0];
-		assertThat(response.getContentAsByteArray()).as("Invalid content").isEqualTo(expecteds);
+		assertThat(response.getContentAsByteArray()).as("Invalid content").isEmpty();
 	}
 
 	@Test
-	public void filterMatchWeakEtag() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterMatchWeakEtag() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		String etag = "\"0b10a8db164e0754105b7a99be72e3fe5\"";
 		request.addHeader("If-None-Match", "W/" + etag);
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
-			byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+			byte[] responseBody = "Hello World".getBytes(UTF_8);
 			FileCopyUtils.copy(responseBody, filterResponse.getOutputStream());
 			filterResponse.setContentLength(responseBody.length);
 		};
@@ -145,13 +145,12 @@ public class ShallowEtagHeaderFilterTests {
 		assertThat(response.getStatus()).as("Invalid status").isEqualTo(304);
 		assertThat(response.getHeader("ETag")).as("Invalid ETag").isEqualTo("\"0b10a8db164e0754105b7a99be72e3fe5\"");
 		assertThat(response.containsHeader("Content-Length")).as("Response has Content-Length header").isFalse();
-		byte[] expecteds = new byte[0];
-		assertThat(response.getContentAsByteArray()).as("Invalid content").isEqualTo(expecteds);
+		assertThat(response.getContentAsByteArray()).as("Invalid content").isEmpty();
 	}
 
 	@Test
-	public void filterWriter() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterWriter() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		String etag = "\"0b10a8db164e0754105b7a99be72e3fe5\"";
 		request.addHeader("If-None-Match", etag);
 		MockHttpServletResponse response = new MockHttpServletResponse();
@@ -167,16 +166,15 @@ public class ShallowEtagHeaderFilterTests {
 		assertThat(response.getStatus()).as("Invalid status").isEqualTo(304);
 		assertThat(response.getHeader("ETag")).as("Invalid ETag").isEqualTo("\"0b10a8db164e0754105b7a99be72e3fe5\"");
 		assertThat(response.containsHeader("Content-Length")).as("Response has Content-Length header").isFalse();
-		byte[] expecteds = new byte[0];
-		assertThat(response.getContentAsByteArray()).as("Invalid content").isEqualTo(expecteds);
+		assertThat(response.getContentAsByteArray()).as("Invalid content").isEmpty();
 	}
 
 	@Test  // SPR-12960
-	public void filterWriterWithDisabledCaching() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterWriterWithDisabledCaching() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK);
@@ -192,11 +190,11 @@ public class ShallowEtagHeaderFilterTests {
 	}
 
 	@Test
-	public void filterSendError() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterSendError() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			response.setContentLength(100);
@@ -212,11 +210,11 @@ public class ShallowEtagHeaderFilterTests {
 	}
 
 	@Test
-	public void filterSendErrorMessage() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterSendErrorMessage() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			response.setContentLength(100);
@@ -233,11 +231,11 @@ public class ShallowEtagHeaderFilterTests {
 	}
 
 	@Test
-	public void filterSendRedirect() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterSendRedirect() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			response.setContentLength(100);
@@ -254,11 +252,11 @@ public class ShallowEtagHeaderFilterTests {
 	}
 
 	@Test // SPR-13717
-	public void filterFlushResponse() throws Exception {
-		final MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
+	void filterFlushResponse() throws Exception {
+		MockHttpServletRequest request = new MockHttpServletRequest("GET", "/hotels");
 		MockHttpServletResponse response = new MockHttpServletResponse();
 
-		final byte[] responseBody = "Hello World".getBytes(StandardCharsets.UTF_8);
+		byte[] responseBody = "Hello World".getBytes(UTF_8);
 		FilterChain filterChain = (filterRequest, filterResponse) -> {
 			assertThat(filterRequest).as("Invalid request passed").isEqualTo(request);
 			((HttpServletResponse) filterResponse).setStatus(HttpServletResponse.SC_OK);