Update to latest Reactor 3.1 API changes

Issue: SPR-15318

spring-web/src/main/java/org/springframework/http/codec/DecoderHttpMessageReader.java

@@ -90,7 +90,7 @@ public class DecoderHttpMessageReader<T> implements HttpMessageReader<T> {
 		MediaType contentType = getContentType(message);
 		return this.decoder
 				.decode(message.getBody(), elementType, contentType, hints)
-				.mapError(this::mapError);
+				.onErrorMap(this::mapError);
 	}
 
 	@Override
@@ -100,7 +100,7 @@ public class DecoderHttpMessageReader<T> implements HttpMessageReader<T> {
 		MediaType contentType = getContentType(message);
 		return this.decoder
 				.decodeToMono(message.getBody(), elementType, contentType, hints)
-				.mapError(this::mapError);
+				.onErrorMap(this::mapError);
 	}
 
 	private MediaType getContentType(HttpMessage inputMessage) {

spring-web/src/main/java/org/springframework/http/codec/EncoderHttpMessageWriter.java

@@ -99,7 +99,7 @@ public class EncoderHttpMessageWriter<T> implements HttpMessageWriter<T> {
 
 		Flux<DataBuffer> body = this.encoder
 				.encode(inputStream, message.bufferFactory(), elementType, contentType, hints)
-				.mapError(this::mapError);
+				.onErrorMap(this::mapError);
 
 		return isStreamingMediaType(contentType) ?
 				message.writeAndFlushWith(body.map(Flux::just)) :

spring-web/src/main/java/org/springframework/http/server/reactive/ReactorHttpHandlerAdapter.java

@@ -57,7 +57,7 @@ public class ReactorHttpHandlerAdapter
 		ReactorServerHttpResponse resp = new ReactorServerHttpResponse(response, bufferFactory);
 
 		return this.httpHandler.handle(req, resp)
-				.switchOnError(ex -> {
+				.onErrorResume(ex -> {
 					logger.error("Could not complete request", ex);
 					response.status(HttpResponseStatus.INTERNAL_SERVER_ERROR);
 					return Mono.empty();

spring-web/src/main/java/org/springframework/http/server/reactive/RxNettyHttpHandlerAdapter.java

@@ -66,7 +66,7 @@ public class RxNettyHttpHandlerAdapter implements RequestHandler<ByteBuf, ByteBu
 		RxNettyServerHttpResponse response = new RxNettyServerHttpResponse(nativeResponse, bufferFactory);
 
 		Publisher<Void> result = this.httpHandler.handle(request, response)
-				.switchOnError(ex -> {
+				.onErrorResume(ex -> {
 					logger.error("Could not complete request", ex);
 					nativeResponse.setStatus(HttpResponseStatus.INTERNAL_SERVER_ERROR);
 					return Mono.empty();

spring-web/src/main/java/org/springframework/web/server/adapter/HttpWebHandlerAdapter.java

@@ -76,7 +76,7 @@ public class HttpWebHandlerAdapter extends WebHandlerDecorator implements HttpHa
 	public Mono<Void> handle(ServerHttpRequest request, ServerHttpResponse response) {
 		ServerWebExchange exchange = createExchange(request, response);
 		return getDelegate().handle(exchange)
-				.switchOnError(ex -> {
+				.onErrorResume(ex -> {
 					if (logger.isDebugEnabled()) {
 						logger.debug("Could not complete request", ex);
 					}

spring-web/src/main/java/org/springframework/web/server/handler/ExceptionHandlingWebHandler.java

@@ -99,7 +99,7 @@ public class ExceptionHandlingWebHandler extends WebHandlerDecorator {
 		}
 
 		for (WebExceptionHandler handler : this.exceptionHandlers) {
-			completion = completion.switchOnError(ex -> handler.handle(exchange, ex));
+			completion = completion.onErrorResume(ex -> handler.handle(exchange, ex));
 		}
 
 		return completion;

spring-web/src/test/java/org/springframework/http/server/reactive/ServerHttpResponseTests.java

@@ -96,7 +96,7 @@ public class ServerHttpResponseTests {
 	public void writeWithError() throws Exception {
 		TestServerHttpResponse response = new TestServerHttpResponse();
 		IllegalStateException error = new IllegalStateException("boo");
-		response.writeWith(Flux.error(error)).switchOnError(ex -> Mono.empty()).block();
+		response.writeWith(Flux.error(error)).onErrorResume(ex -> Mono.empty()).block();
 
 		assertFalse(response.statusCodeWritten);
 		assertFalse(response.headersWritten);

spring-webflux/src/main/java/org/springframework/web/reactive/DispatcherHandler.java

@@ -141,7 +141,7 @@ public class DispatcherHandler implements WebHandler, ApplicationContextAware {
 
 	private Mono<Void> handleResult(ServerWebExchange exchange, HandlerResult result) {
 		return getResultHandler(result).handleResult(exchange, result)
-				.switchOnError(ex -> result.applyExceptionHandler(ex).flatMap(exceptionResult ->
+				.onErrorResume(ex -> result.applyExceptionHandler(ex).flatMap(exceptionResult ->
 						getResultHandler(exceptionResult).handleResult(exchange, exceptionResult)));
 	}
 

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/DefaultServerRequest.java

@@ -120,13 +120,13 @@ class DefaultServerRequest implements ServerRequest {
 	@Override
 	public <T> Mono<T> bodyToMono(Class<? extends T> elementClass) {
 		Mono<T> mono = body(BodyExtractors.toMono(elementClass));
-		return mono.mapError(UnsupportedMediaTypeException.class, ERROR_MAPPER);
+		return mono.onErrorMap(UnsupportedMediaTypeException.class, ERROR_MAPPER);
 	}
 
 	@Override
 	public <T> Flux<T> bodyToFlux(Class<? extends T> elementClass) {
 		Flux<T> flux = body(BodyExtractors.toFlux(elementClass));
-		return flux.mapError(UnsupportedMediaTypeException.class, ERROR_MAPPER);
+		return flux.onErrorMap(UnsupportedMediaTypeException.class, ERROR_MAPPER);
 	}
 
 	@Override

spring-webflux/src/main/java/org/springframework/web/reactive/function/server/RouterFunctions.java

@@ -234,7 +234,7 @@ public abstract class RouterFunctions {
 					.defaultIfEmpty(notFound())
 					.flatMap(handlerFunction -> wrapException(() -> handlerFunction.handle(request)))
 					.flatMap(response -> wrapException(() -> response.writeTo(exchange, strategies)))
-					.switchOnError(ResponseStatusException.class,
+					.onErrorResume(ResponseStatusException.class,
 							ex -> {
 								exchange.getResponse().setStatusCode(ex.getStatus());
 								if (ex.getMessage() != null) {

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

@@ -117,7 +117,7 @@ public abstract class AbstractMessageReaderArgumentResolver extends HandlerMetho
 				Map<String, Object> readHints = Collections.emptyMap();
 				if (adapter != null && adapter.isMultiValue()) {
 					Flux<?> flux = reader.read(bodyType, elementType, request, response, readHints);
-					flux = flux.onErrorResumeWith(ex -> Flux.error(getReadError(bodyParameter, ex)));
+					flux = flux.onErrorResume(ex -> Flux.error(getReadError(bodyParameter, ex)));
 					if (isBodyRequired || !adapter.supportsEmpty()) {
 						flux = flux.switchIfEmpty(Flux.error(getRequiredBodyError(bodyParameter)));
 					}
@@ -130,7 +130,7 @@ public abstract class AbstractMessageReaderArgumentResolver extends HandlerMetho
 				}
 				else {
 					Mono<?> mono = reader.readMono(bodyType, elementType, request, response, readHints);
-					mono = mono.switchOnError(ex -> Mono.error(getReadError(bodyParameter, ex)));
+					mono = mono.onErrorResume(ex -> Mono.error(getReadError(bodyParameter, ex)));
 					if (isBodyRequired || (adapter != null && !adapter.supportsEmpty())) {
 						mono = mono.switchIfEmpty(Mono.error(getRequiredBodyError(bodyParameter)));
 					}

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

@@ -189,7 +189,7 @@ public class RequestMappingHandlerAdapter implements HandlerAdapter, Application
 				.then(() -> this.methodResolver.getRequestMappingMethod(handlerMethod)
 						.invoke(exchange, bindingContext)
 						.doOnNext(result -> result.setExceptionHandler(exceptionHandler))
-						.switchOnError(exceptionHandler));
+						.onErrorResume(exceptionHandler));
 	}
 
 	private Mono<HandlerResult> handleException(Throwable ex, HandlerMethod handlerMethod,