Adapt to GraphQL over HTTP spec changes

As of graphql/graphql-over-http#215, the official media type for GraphQL
HTTP responses is now `"application/graphql-response+json"` instead of
`"application/graphql+json"`. The latter is now deprecated and support
will be removed in the future.

This commit now favors the new media type.
HTTP Clients are still supposed to send requests with the
`"application/json"` content type.

Closes gh-563

spring-graphql/src/main/java/org/springframework/graphql/client/HttpGraphQlTransport.java

@@ -44,6 +44,10 @@ final class HttpGraphQlTransport implements GraphQlTransport {
 	private static final ParameterizedTypeReference<Map<String, Object>> MAP_TYPE =
 			new ParameterizedTypeReference<Map<String, Object>>() {};
 
+	// To be removed in favor of Framework's MediaType.APPLICATION_GRAPHQL_RESPONSE
+	private static final MediaType APPLICATION_GRAPHQL_RESPONSE =
+			new MediaType("application", "graphql-response+json");
+
 
 	private final WebClient webClient;
 
@@ -65,10 +69,11 @@ private static MediaType initContentType(WebClient webClient) {
 
 
 	@Override
+	@SuppressWarnings("removal")
 	public Mono<GraphQlResponse> execute(GraphQlRequest request) {
 		return this.webClient.post()
 				.contentType(this.contentType)
-				.accept(MediaType.APPLICATION_JSON, MediaType.APPLICATION_GRAPHQL)
+				.accept(MediaType.APPLICATION_JSON, APPLICATION_GRAPHQL_RESPONSE, MediaType.APPLICATION_GRAPHQL)
 				.bodyValue(request.toMap())
 				.retrieve()
 				.bodyToMono(MAP_TYPE)

spring-graphql/src/main/java/org/springframework/graphql/server/webflux/GraphQlHttpHandler.java

@@ -43,11 +43,16 @@ public class GraphQlHttpHandler {
 
 	private static final Log logger = LogFactory.getLog(GraphQlHttpHandler.class);
 
+	// To be removed in favor of Framework's MediaType.APPLICATION_GRAPHQL_RESPONSE
+	private static final MediaType APPLICATION_GRAPHQL_RESPONSE =
+			new MediaType("application", "graphql-response+json");
+
 	private static final ParameterizedTypeReference<Map<String, Object>> MAP_PARAMETERIZED_TYPE_REF =
 			new ParameterizedTypeReference<Map<String, Object>>() {};
 
+	@SuppressWarnings("removal")
 	private static final List<MediaType> SUPPORTED_MEDIA_TYPES =
-			Arrays.asList(MediaType.APPLICATION_GRAPHQL, MediaType.APPLICATION_JSON);
+			Arrays.asList(APPLICATION_GRAPHQL_RESPONSE, MediaType.APPLICATION_JSON, MediaType.APPLICATION_GRAPHQL);
 
 	private final WebGraphQlHandler graphQlHandler;
 

spring-graphql/src/main/java/org/springframework/graphql/server/webmvc/GraphQlHttpHandler.java

@@ -55,8 +55,13 @@ public class GraphQlHttpHandler {
 	private static final ParameterizedTypeReference<Map<String, Object>> MAP_PARAMETERIZED_TYPE_REF =
 			new ParameterizedTypeReference<Map<String, Object>>() {};
 
+	// To be removed in favor of Framework's MediaType.APPLICATION_GRAPHQL_RESPONSE
+	private static final MediaType APPLICATION_GRAPHQL_RESPONSE =
+			new MediaType("application", "graphql-response+json");
+
+	@SuppressWarnings("removal")
 	private static final List<MediaType> SUPPORTED_MEDIA_TYPES =
-			Arrays.asList(MediaType.APPLICATION_GRAPHQL, MediaType.APPLICATION_JSON);
+			Arrays.asList(APPLICATION_GRAPHQL_RESPONSE, MediaType.APPLICATION_JSON, MediaType.APPLICATION_GRAPHQL);
 
 	private final IdGenerator idGenerator = new AlternativeJdkIdGenerator();
 

spring-graphql/src/test/java/org/springframework/graphql/client/WebGraphQlClientBuilderTests.java

@@ -189,13 +189,14 @@ void contentTypeDefault() {
 
 	@Test
 	void contentTypeOverride() {
+		MediaType testMediaType = new MediaType("application", "graphql-request+json");
 
 		HttpBuilderSetup setup = new HttpBuilderSetup();
-		setup.initBuilder().header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_GRAPHQL_VALUE).build()
+		setup.initBuilder().header(HttpHeaders.CONTENT_TYPE, "application/graphql-request+json").build()
 				.document(DOCUMENT).execute().block(TIMEOUT);
 
 		WebGraphQlRequest request = setup.getActualRequest();
-		assertThat(request.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_GRAPHQL);
+		assertThat(request.getHeaders().getContentType()).isEqualTo(testMediaType);
 
 	}
 

spring-graphql/src/test/java/org/springframework/graphql/server/webflux/GraphQlHttpHandlerTests.java

@@ -64,12 +64,12 @@ void shouldProduceApplicationJsonByDefault() {
 	@Test
 	void shouldProduceApplicationGraphQl() {
 		MockServerHttpRequest httpRequest = MockServerHttpRequest.post("/")
-				.contentType(MediaType.APPLICATION_GRAPHQL).accept(MediaType.APPLICATION_GRAPHQL).build();
+				.contentType(MediaType.APPLICATION_JSON).accept(MediaType.APPLICATION_GRAPHQL_RESPONSE).build();
 
 		MockServerHttpResponse httpResponse = handleRequest(
 				httpRequest, this.greetingHandler, Collections.singletonMap("query", "{greeting}"));
 
-		assertThat(httpResponse.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_GRAPHQL);
+		assertThat(httpResponse.getHeaders().getContentType()).isEqualTo(MediaType.APPLICATION_GRAPHQL_RESPONSE);
 	}
 
 	@Test
@@ -90,7 +90,8 @@ void locale() {
 				.toHttpHandlerWebFlux();
 
 		MockServerHttpRequest httpRequest = MockServerHttpRequest.post("/")
-				.contentType(MediaType.APPLICATION_GRAPHQL).accept(MediaType.APPLICATION_GRAPHQL).acceptLanguageAsLocales(Locale.FRENCH).build();
+				.contentType(MediaType.APPLICATION_JSON).accept(MediaType.APPLICATION_GRAPHQL_RESPONSE)
+				.acceptLanguageAsLocales(Locale.FRENCH).build();
 
 		MockServerHttpResponse httpResponse = handleRequest(
 				httpRequest, handler, Collections.singletonMap("query", "{greeting}"));
@@ -106,7 +107,7 @@ void shouldSetExecutionId() {
 				.toHttpHandlerWebFlux();
 
 		MockServerHttpRequest httpRequest = MockServerHttpRequest.post("/")
-				.contentType(MediaType.APPLICATION_GRAPHQL).accept(MediaType.APPLICATION_GRAPHQL).build();
+				.contentType(MediaType.APPLICATION_JSON).accept(MediaType.APPLICATION_GRAPHQL_RESPONSE).build();
 
 		MockServerHttpResponse httpResponse = handleRequest(
 				httpRequest, handler, Collections.singletonMap("query", "{showId}"));

spring-graphql/src/test/java/org/springframework/graphql/server/webmvc/GraphQlHttpHandlerTests.java

@@ -64,9 +64,9 @@ void shouldProduceApplicationJsonByDefault() throws Exception {
 
 	@Test
 	void shouldProduceApplicationGraphQl() throws Exception {
-		MockHttpServletRequest servletRequest = createServletRequest("{\"query\":\"{ greeting }\"}", MediaType.APPLICATION_GRAPHQL_VALUE);
+		MockHttpServletRequest servletRequest = createServletRequest("{\"query\":\"{ greeting }\"}", MediaType.APPLICATION_GRAPHQL_RESPONSE_VALUE);
 		MockHttpServletResponse servletResponse = handleRequest(servletRequest, this.greetingHandler);
-		assertThat(servletResponse.getContentType()).isEqualTo(MediaType.APPLICATION_GRAPHQL_VALUE);
+		assertThat(servletResponse.getContentType()).isEqualTo(MediaType.APPLICATION_GRAPHQL_RESPONSE_VALUE);
 	}
 
 	@Test
@@ -81,7 +81,7 @@ void locale() throws Exception {
 		GraphQlHttpHandler handler = GraphQlSetup.schemaContent("type Query { greeting: String }")
 				.queryFetcher("greeting", (env) -> "Hello in " + env.getLocale())
 				.toHttpHandler();
-		MockHttpServletRequest servletRequest = createServletRequest("{\"query\":\"{ greeting }\"}", MediaType.APPLICATION_GRAPHQL_VALUE);
+		MockHttpServletRequest servletRequest = createServletRequest("{\"query\":\"{ greeting }\"}", MediaType.APPLICATION_GRAPHQL_RESPONSE_VALUE);
 		LocaleContextHolder.setLocale(Locale.FRENCH);
 
 		try {
@@ -101,7 +101,7 @@ void shouldSetExecutionId() throws Exception {
 				.queryFetcher("showId", (env) -> env.getExecutionId().toString())
 				.toHttpHandler();
 
-		MockHttpServletRequest servletRequest = createServletRequest("{\"query\":\"{ showId }\"}", MediaType.APPLICATION_GRAPHQL_VALUE);
+		MockHttpServletRequest servletRequest = createServletRequest("{\"query\":\"{ showId }\"}", MediaType.APPLICATION_GRAPHQL_RESPONSE_VALUE);
 
 		MockHttpServletResponse servletResponse = handleRequest(servletRequest, handler);
 		DocumentContext document = JsonPath.parse(servletResponse.getContentAsString());