Merge branch '5.1.x'

Author: bclozel

spring-webflux/src/main/java/org/springframework/web/reactive/result/method/annotation/RequestMappingHandlerAdapter.java

@@ -29,6 +29,7 @@
 import org.springframework.context.ApplicationContextAware;
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.core.ReactiveAdapterRegistry;
+import org.springframework.http.HttpHeaders;
 import org.springframework.http.codec.HttpMessageReader;
 import org.springframework.http.codec.ServerCodecConfigurer;
 import org.springframework.lang.Nullable;
@@ -209,6 +210,9 @@ private Mono<HandlerResult> handleException(Throwable exception, HandlerMethod h
 
 		// Success and error responses may use different content types
 		exchange.getAttributes().remove(HandlerMapping.PRODUCIBLE_MEDIA_TYPES_ATTRIBUTE);
+		if (!exchange.getResponse().isCommitted()) {
+			exchange.getResponse().getHeaders().remove(HttpHeaders.CONTENT_TYPE);
+		}
 
 		InvocableHandlerMethod invocable = this.methodResolver.getExceptionHandlerMethod(exception, handlerMethod);
 		if (invocable != null) {

spring-webflux/src/test/java/org/springframework/web/reactive/result/method/annotation/RequestMappingExceptionHandlingIntegrationTests.java

@@ -93,7 +93,7 @@ public void exceptionAfterSeveralItems() {
 	public void exceptionFromMethodWithProducesCondition() throws Exception {
 		try {
 			HttpHeaders headers = new HttpHeaders();
-			headers.add("Accept", "text/csv, application/problem+json");
+			headers.add("Accept", "text/plain, application/problem+json");
 			performGet("/SPR-16318", headers, String.class).getBody();
 			fail();
 		}
@@ -152,9 +152,9 @@ public Flux<String> errors() {
 					});
 		}
 
-		@GetMapping(path = "/SPR-16318", produces = "text/csv")
-		public String handleCsv() throws Exception {
-			throw new Spr16318Exception();
+		@GetMapping(path = "/SPR-16318", produces = "text/plain")
+		public Mono<String> handleTextPlain() throws Exception {
+			return Mono.error(new Spr16318Exception());
 		}
 
 		@ExceptionHandler