Polish "Simplify code"

See gh-18342

spring-boot-project/spring-boot-tools/spring-boot-gradle-plugin/src/main/java/org/springframework/boot/gradle/tasks/bundling/BootArchiveSupport.java

@@ -143,8 +143,8 @@ class BootArchiveSupport {
 	}
 
 	private boolean isZip(InputStream inputStream) throws IOException {
-		for (byte b : ZIP_FILE_HEADER) {
-			if (inputStream.read() != b) {
+		for (byte headerByte : ZIP_FILE_HEADER) {
+			if (inputStream.read() != headerByte) {
 				return false;
 			}
 		}

spring-boot-project/spring-boot/src/test/java/org/springframework/boot/web/embedded/tomcat/TomcatServletWebServerFactoryTests.java

@@ -68,7 +68,6 @@ import org.mockito.InOrder;
 import org.springframework.boot.testsupport.system.CapturedOutput;
 import org.springframework.boot.web.server.PortInUseException;
 import org.springframework.boot.web.server.WebServerException;
-import org.springframework.boot.web.servlet.ServletContextInitializer;
 import org.springframework.boot.web.servlet.server.AbstractServletWebServerFactory;
 import org.springframework.boot.web.servlet.server.AbstractServletWebServerFactoryTests;
 import org.springframework.core.io.ByteArrayResource;
@@ -544,7 +543,7 @@ class TomcatServletWebServerFactoryTests extends AbstractServletWebServerFactory
 	@Test
 	void registerJspServletWithDefaultLoadOnStartup() {
 		TomcatServletWebServerFactory factory = new TomcatServletWebServerFactory(0);
-		factory.addInitializers(servletContext -> servletContext.addServlet("manually-registered-jsp-servlet", JspServlet.class));
+		factory.addInitializers((context) -> context.addServlet("manually-registered-jsp-servlet", JspServlet.class));
 		this.webServer = factory.getWebServer();
 		this.webServer.start();
 	}