Add missing @FunctionalInterface in oauth2 modules

Fixes gh-8020

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/OAuth2AuthorizedClientManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -39,6 +39,7 @@ import org.springframework.security.oauth2.client.web.OAuth2AuthorizedClientRepo
  * @see OAuth2AuthorizedClientService
  * @see OAuth2AuthorizedClientRepository
  */
+@FunctionalInterface
 public interface OAuth2AuthorizedClientManager {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/OAuth2AuthorizedClientProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -29,6 +29,7 @@ import org.springframework.security.oauth2.core.AuthorizationGrantType;
  * @see OAuth2AuthorizationContext
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-1.3">Section 1.3 Authorization Grant</a>
  */
+@FunctionalInterface
 public interface OAuth2AuthorizedClientProvider {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/ReactiveOAuth2AuthorizedClientManager.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -39,6 +39,7 @@ import reactor.core.publisher.Mono;
  * @see ReactiveOAuth2AuthorizedClientService
  * @see ServerOAuth2AuthorizedClientRepository
  */
+@FunctionalInterface
 public interface ReactiveOAuth2AuthorizedClientManager {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/ReactiveOAuth2AuthorizedClientProvider.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -29,6 +29,7 @@ import reactor.core.publisher.Mono;
  * @see OAuth2AuthorizationContext
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-1.3">Section 1.3 Authorization Grant</a>
  */
+@FunctionalInterface
 public interface ReactiveOAuth2AuthorizedClientProvider {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/OAuth2AccessTokenResponseClient.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -34,6 +34,7 @@ import org.springframework.security.oauth2.core.endpoint.OAuth2AccessTokenRespon
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-4.1.3">Section 4.1.3 Access Token Request (Authorization Code Grant)</a>
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-4.1.4">Section 4.1.4 Access Token Response (Authorization Code Grant)</a>
  */
+@FunctionalInterface
 public interface OAuth2AccessTokenResponseClient<T extends AbstractOAuth2AuthorizationGrantRequest>  {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/endpoint/ReactiveOAuth2AccessTokenResponseClient.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -34,6 +34,7 @@ import reactor.core.publisher.Mono;
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-4.1.3">Section 4.1.3 Access Token Request (Authorization Code Grant)</a>
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc6749#section-4.1.4">Section 4.1.4 Access Token Response (Authorization Code Grant)</a>
  */
+@FunctionalInterface
 public interface ReactiveOAuth2AccessTokenResponseClient<T extends AbstractOAuth2AuthorizationGrantRequest>  {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/userinfo/OAuth2UserService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -35,6 +35,7 @@ import org.springframework.security.oauth2.core.user.OAuth2User;
  * @param <R> The type of OAuth 2.0 User Request
  * @param <U> The type of OAuth 2.0 User
  */
+@FunctionalInterface
 public interface OAuth2UserService<R extends OAuth2UserRequest, U extends OAuth2User> {
 
 	/**

oauth2/oauth2-client/src/main/java/org/springframework/security/oauth2/client/userinfo/ReactiveOAuth2UserService.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -36,6 +36,7 @@ import reactor.core.publisher.Mono;
  * @param <R> The type of OAuth 2.0 User Request
  * @param <U> The type of OAuth 2.0 User
  */
+@FunctionalInterface
 public interface ReactiveOAuth2UserService<R extends OAuth2UserRequest, U extends OAuth2User> {
 
 	/**

oauth2/oauth2-core/src/main/java/org/springframework/security/oauth2/core/OAuth2TokenValidator.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -23,6 +23,7 @@ package org.springframework.security.oauth2.core;
  * @author Josh Cummings
  * @since 5.1
  */
+@FunctionalInterface
 public interface OAuth2TokenValidator<T extends AbstractOAuth2Token> {
 
 	/**

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/JwtDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2017 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -34,6 +34,7 @@ package org.springframework.security.oauth2.jwt;
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc7515#section-3.1">JWS Compact Serialization</a>
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc7516#section-3.1">JWE Compact Serialization</a>
  */
+@FunctionalInterface
 public interface JwtDecoder {
 
 	/**

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/JwtDecoderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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 @@ package org.springframework.security.oauth2.jwt;
  *
  * @param <C> The type that provides contextual information used to create a specific {@code JwtDecoder}.
  */
+@FunctionalInterface
 public interface JwtDecoderFactory<C> {
 
 	/**

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/ReactiveJwtDecoder.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -36,6 +36,7 @@ import reactor.core.publisher.Mono;
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc7515#section-3.1">JWS Compact Serialization</a>
  * @see <a target="_blank" href="https://tools.ietf.org/html/rfc7516#section-3.1">JWE Compact Serialization</a>
  */
+@FunctionalInterface
 public interface ReactiveJwtDecoder {
 
 	/**

oauth2/oauth2-jose/src/main/java/org/springframework/security/oauth2/jwt/ReactiveJwtDecoderFactory.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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 @@ package org.springframework.security.oauth2.jwt;
  *
  * @param <C> The type that provides contextual information used to create a specific {@code ReactiveJwtDecoder}.
  */
+@FunctionalInterface
 public interface ReactiveJwtDecoderFactory<C> {
 
 	/**

oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/introspection/OpaqueTokenIntrospector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -33,6 +33,7 @@ import org.springframework.security.oauth2.core.OAuth2AuthenticatedPrincipal;
  * @author Josh Cummings
  * @since 5.2
  */
+@FunctionalInterface
 public interface OpaqueTokenIntrospector {
 
 	/**

oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/introspection/ReactiveOpaqueTokenIntrospector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -35,6 +35,7 @@ import org.springframework.security.oauth2.core.OAuth2AuthenticatedPrincipal;
  * @author Josh Cummings
  * @since 5.2
  */
+@FunctionalInterface
 public interface ReactiveOpaqueTokenIntrospector {
 
 	/**

oauth2/oauth2-resource-server/src/main/java/org/springframework/security/oauth2/server/resource/web/BearerTokenResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2018 the original author or authors.
+ * Copyright 2002-2020 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.
@@ -28,6 +28,7 @@ import org.springframework.security.oauth2.core.OAuth2AuthenticationException;
  * @since 5.1
  * @see <a href="https://tools.ietf.org/html/rfc6750#section-2" target="_blank">RFC 6750 Section 2: Authenticated Requests</a>
  */
+@FunctionalInterface
 public interface BearerTokenResolver {
 
 	/**