Support 404 handling for HttpExchange interfaces

Closes gh-32105

spring-web/src/main/java/org/springframework/web/client/support/NotFoundRestClientAdapterDecorator.java

@@ -0,0 +1,76 @@
+/*
+ * Copyright 2002-present 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.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.web.client.support;
+
+import org.jspecify.annotations.Nullable;
+
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.client.HttpClientErrorException;
+import org.springframework.web.service.invoker.HttpExchangeAdapter;
+import org.springframework.web.service.invoker.HttpExchangeAdapterDecorator;
+import org.springframework.web.service.invoker.HttpRequestValues;
+
+/**
+ * {@code HttpExchangeAdapterDecorator} that suppresses the
+ * {@link HttpClientErrorException.NotFound} exception raised on a 404 response
+ * and returns a {@code ResponseEntity} with the status set to
+ * {@link org.springframework.http.HttpStatus#NOT_FOUND} status, or
+ * {@code null} from {@link #exchangeForBody}.
+ *
+ * @author Rossen Stoyanchev
+ * @since 7.0
+ */
+public final class NotFoundRestClientAdapterDecorator extends HttpExchangeAdapterDecorator {
+
+
+	public NotFoundRestClientAdapterDecorator(HttpExchangeAdapter delegate) {
+		super(delegate);
+	}
+
+
+	@Override
+	public <T> @Nullable T exchangeForBody(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
+		try {
+			return super.exchangeForBody(values, bodyType);
+		}
+		catch (HttpClientErrorException.NotFound ex) {
+			return null;
+		}
+	}
+
+	@Override
+	public ResponseEntity<Void> exchangeForBodilessEntity(HttpRequestValues values) {
+		try {
+			return super.exchangeForBodilessEntity(values);
+		}
+		catch (HttpClientErrorException.NotFound ex) {
+			return ResponseEntity.notFound().build();
+		}
+	}
+
+	@Override
+	public <T> ResponseEntity<T> exchangeForEntity(HttpRequestValues values, ParameterizedTypeReference<T> bodyType) {
+		try {
+			return super.exchangeForEntity(values, bodyType);
+		}
+		catch (HttpClientErrorException.NotFound ex) {
+			return ResponseEntity.notFound().build();
+		}
+	}
+
+}

spring-web/src/main/java/org/springframework/web/service/invoker/HttpServiceProxyFactory.java

@@ -140,10 +140,10 @@ public final class HttpServiceProxyFactory {
 
 		private final List<HttpServiceArgumentResolver> customArgumentResolvers = new ArrayList<>();
 
-		private final List<HttpRequestValues.Processor> requestValuesProcessors = new ArrayList<>();
-
 		private @Nullable ConversionService conversionService;
 
+		private final List<HttpRequestValues.Processor> requestValuesProcessors = new ArrayList<>();
+
 		private @Nullable StringValueResolver embeddedValueResolver;
 
 		private Builder() {
@@ -181,6 +181,17 @@ public final class HttpServiceProxyFactory {
 			return this;
 		}
 
+		/**
+		 * Set the {@link ConversionService} to use where input values need to
+		 * be formatted as Strings.
+		 * <p>By default, this is {@link DefaultFormattingConversionService}.
+		 * @return this same builder instance
+		 */
+		public Builder conversionService(ConversionService conversionService) {
+			this.conversionService = conversionService;
+			return this;
+		}
+
 		/**
 		 * Register an {@link HttpRequestValues} processor that can further
 		 * customize request values based on the method and all arguments.
@@ -193,17 +204,6 @@ public final class HttpServiceProxyFactory {
 			return this;
 		}
 
-		/**
-		 * Set the {@link ConversionService} to use where input values need to
-		 * be formatted as Strings.
-		 * <p>By default this is {@link DefaultFormattingConversionService}.
-		 * @return this same builder instance
-		 */
-		public Builder conversionService(ConversionService conversionService) {
-			this.conversionService = conversionService;
-			return this;
-		}
-
 		/**
 		 * Set the {@link StringValueResolver} to use for resolving placeholders
 		 * and expressions embedded in {@link HttpExchange#url()}.

spring-web/src/main/java/org/springframework/web/service/invoker/ReactorHttpExchangeAdapterDecorator.java

@@ -43,7 +43,7 @@ public class ReactorHttpExchangeAdapterDecorator extends HttpExchangeAdapterDeco
 
 
 	/**
-	 * Return the wrapped delgate {@code HttpExchangeAdapter}.
+	 * Return the wrapped delegate {@code HttpExchangeAdapter}.
 	 */
 	@Override
 	public ReactorHttpExchangeAdapter getHttpExchangeAdapter() {