Mark log file endpoint as producing text/plain

Closes gh-16188

Author: wilkinsona

Diff for: spring-boot-project/spring-boot-actuator/src/main/java/org/springframework/boot/actuate/logging/LogFileWebEndpoint.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2019 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 @@ public LogFileWebEndpoint(Environment environment) {
 		this(environment, null);
 	}
 
-	@ReadOperation
+	@ReadOperation(produces = "text/plain")
 	public Resource logFile() {
 		Resource logFileResource = getLogFileResource();
 		if (logFileResource == null || !logFileResource.isReadable()) {

Diff for: spring-boot-project/spring-boot-actuator/src/test/java/org/springframework/boot/actuate/logging/LogFileWebEndpointWebIntegrationTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2017 the original author or authors.
+ * Copyright 2012-2019 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.
@@ -31,6 +31,7 @@
 import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.core.env.Environment;
+import org.springframework.http.MediaType;
 import org.springframework.test.web.reactive.server.WebTestClient;
 import org.springframework.util.FileCopyUtils;
 
@@ -71,6 +72,14 @@ public void getRequestProducesResponseWithLogFile() {
 				.expectBody(String.class).isEqualTo("--TEST--");
 	}
 
+	@Test
+	public void getRequestThatAcceptsTextPlainProducesResponseWithLogFile() {
+		TestPropertyValues.of("logging.file:" + this.logFile.getAbsolutePath())
+				.applyTo(context);
+		client.get().uri("/actuator/logfile").accept(MediaType.TEXT_PLAIN).exchange()
+				.expectStatus().isOk().expectBody(String.class).isEqualTo("--TEST--");
+	}
+
 	@Configuration
 	static class TestConfiguration {