Improve ExtendedWebExchangeDataBinder implementation

Close gh-28646

Author: rstoyanchev

spring-web/src/main/java/org/springframework/web/bind/support/WebExchangeDataBinder.java

@@ -84,8 +84,8 @@ public Mono<Void> bind(ServerWebExchange exchange) {
 	}
 
 	/**
-	 * Protected method to obtain the values for data binding. By default this
-	 * method delegates to {@link #extractValuesToBind(ServerWebExchange)}.
+	 * Obtain the values for data binding. By default, this delegates to
+	 * {@link #extractValuesToBind(ServerWebExchange)}.
 	 * @param exchange the current exchange
 	 * @return a map of bind values
 	 * @since 5.3

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

@@ -18,14 +18,11 @@
 
 import java.util.Collections;
 import java.util.Map;
-import java.util.TreeMap;
 
 import reactor.core.publisher.Mono;
 
-import org.springframework.http.codec.multipart.Part;
 import org.springframework.lang.Nullable;
 import org.springframework.ui.Model;
-import org.springframework.util.MultiValueMap;
 import org.springframework.validation.support.BindingAwareConcurrentModel;
 import org.springframework.web.bind.support.WebBindingInitializer;
 import org.springframework.web.bind.support.WebExchangeDataBinder;
@@ -127,21 +124,9 @@ public ExtendedWebExchangeDataBinder(@Nullable Object target, String objectName)
 
 		@Override
 		public Mono<Map<String, Object>> getValuesToBind(ServerWebExchange exchange) {
-			Map<String, String> vars = exchange.getAttributeOrDefault(
-					HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, Collections.emptyMap());
-			MultiValueMap<String, String> queryParams = exchange.getRequest().getQueryParams();
-			Mono<MultiValueMap<String, String>> formData = exchange.getFormData();
-			Mono<MultiValueMap<String, Part>> multipartData = exchange.getMultipartData();
-
-			return Mono.zip(Mono.just(vars), Mono.just(queryParams), formData, multipartData)
-					.map(tuple -> {
-						Map<String, Object> result = new TreeMap<>();
-						result.putAll(tuple.getT1());
-						tuple.getT2().forEach((key, values) -> addBindValue(result, key, values));
-						tuple.getT3().forEach((key, values) -> addBindValue(result, key, values));
-						tuple.getT4().forEach((key, values) -> addBindValue(result, key, values));
-						return result;
-					});
+			return super.getValuesToBind(exchange).doOnNext(map ->
+					map.putAll(exchange.<Map<String, String>>getAttributeOrDefault(
+							HandlerMapping.URI_TEMPLATE_VARIABLES_ATTRIBUTE, Collections.emptyMap())));
 		}
 	}