Update Deprecated Property in Opaque Token Introspectors

Update NimbusOpaqueTokenIntrospector and NimbusReactiveOpaqueTokenIntrospector to use MediaType.APPLICATION_JSON instead of the deprecated MediaType.APPLICATION_JSON_UTF8

Closes gh-9353

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -109,7 +109,7 @@ public class NimbusOpaqueTokenIntrospector implements OpaqueTokenIntrospector {
 
 	private HttpHeaders requestHeaders() {
 		HttpHeaders headers = new HttpHeaders();
-		headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON_UTF8));
+		headers.setAccept(Collections.singletonList(MediaType.APPLICATION_JSON));
 		return headers;
 	}
 

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2019 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -106,7 +106,7 @@ public class NimbusReactiveOpaqueTokenIntrospector implements ReactiveOpaqueToke
 		// @formatter:off
 		return this.webClient.post()
 				.uri(this.introspectionUri)
-				.header(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_UTF8_VALUE)
+				.header(HttpHeaders.ACCEPT, MediaType.APPLICATION_JSON_VALUE)
 				.body(BodyInserters.fromFormData("token", token))
 				.exchange();
 		// @formatter:on

oauth2/oauth2-resource-server/src/test/java/org/springframework/security/oauth2/server/resource/introspection/NimbusReactiveOpaqueTokenIntrospectorTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2020 the original author or authors.
+ * Copyright 2002-2021 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.
@@ -244,7 +244,7 @@ public class NimbusReactiveOpaqueTokenIntrospectorTests {
 		given(clientResponse.statusCode()).willReturn(HttpStatus.OK);
 		given(clientResponse.bodyToMono(String.class)).willReturn(Mono.just(response));
 		ClientResponse.Headers headers = mock(ClientResponse.Headers.class);
-		given(headers.contentType()).willReturn(Optional.of(MediaType.APPLICATION_JSON_UTF8));
+		given(headers.contentType()).willReturn(Optional.of(MediaType.APPLICATION_JSON));
 		given(clientResponse.headers()).willReturn(headers);
 		given(spec.exchange()).willReturn(Mono.just(clientResponse));
 		return webClient;