Add @FunctionalInterface to remaining public and protected interfaces

See gh-6857

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/HeapdumpMvcEndpoint.java

@@ -168,6 +168,7 @@ public class HeapdumpMvcEndpoint extends AbstractNamedMvcEndpoint {
 	/**
 	 * Strategy interface used to dump the heap to a file.
 	 */
+	@FunctionalInterface
 	protected interface HeapDumper {
 
 		/**

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/endpoint/mvc/NamePatternFilter.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -76,7 +76,7 @@ abstract class NamePatternFilter<T> {
 	/**
 	 * Callback used to add a name.
 	 */
-	protected interface NameCallback {
+	interface NameCallback {
 
 		void addName(String name);
 

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/dropwizard/ReservoirFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -26,6 +26,7 @@ import com.codahale.metrics.Reservoir;
  * @author Phillip Webb
  * @since 1.5.0
  */
+@FunctionalInterface
 public interface ReservoirFactory {
 
 	/**

spring-boot-actuator/src/main/java/org/springframework/boot/actuate/metrics/util/SimpleInMemoryRepository.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2016 the original author or authors.
+ * Copyright 2012-2017 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.
@@ -102,6 +102,7 @@ public class SimpleInMemoryRepository<T> {
 	 *
 	 * @param <T> the value type
 	 */
+	@FunctionalInterface
 	public interface Callback<T> {
 
 		/**