Form content length falsify

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/filter/FormFilter.java

@@ -125,6 +125,7 @@ static HttpServletRequest getRequestWithBodyFromRequestParameters(HttpServletReq
 			Map.Entry<String, String[]> entry = entryIterator.next();
 			String name = entry.getKey();
 			List<String> values = Arrays.asList(entry.getValue());
+			boolean valueWritten = false;
 			for (Iterator<String> valueIterator = values.iterator(); valueIterator.hasNext();) {
 				String value = valueIterator.next();
 				List<String> queryValues = queryParams.get(name);
@@ -139,9 +140,10 @@ static HttpServletRequest getRequestWithBodyFromRequestParameters(HttpServletReq
 							writer.write('&');
 						}
 					}
+					valueWritten = true;
 				}
 			}
-			if (entryIterator.hasNext()) {
+			if (valueWritten && entryIterator.hasNext()) {
 				writer.append('&');
 			}
 		}

spring-cloud-gateway-server-mvc/src/test/java/org/springframework/cloud/gateway/server/mvc/filter/FormFilterTests.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2013-2023 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.cloud.gateway.server.mvc.filter;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
+
+import jakarta.servlet.ServletException;
+import jakarta.servlet.ServletRequest;
+import org.junit.jupiter.api.Test;
+import org.testcontainers.shaded.org.apache.commons.io.IOUtils;
+
+import org.springframework.http.MediaType;
+import org.springframework.mock.web.MockFilterChain;
+import org.springframework.mock.web.MockHttpServletRequest;
+import org.springframework.mock.web.MockHttpServletResponse;
+import org.springframework.test.web.servlet.request.MockMvcRequestBuilders;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * @author Lu lu
+ */
+public class FormFilterTests {
+
+	@Test
+	public void sameContentLengthWithOriginalPostFormUrlEncodeTest() throws ServletException, IOException {
+
+		byte[] content = "baz=bam".getBytes();
+
+		MockHttpServletRequest request = MockMvcRequestBuilders.post("http://localhost/post?foo=fooquery")
+				.contentType(MediaType.APPLICATION_FORM_URLENCODED).content(content).buildRequest(null);
+		MockHttpServletResponse response = new MockHttpServletResponse();
+		MockFilterChain mockFilterChain = new MockFilterChain();
+		FormFilter formFilter = new FormFilter();
+		formFilter.doFilter(request, response, mockFilterChain);
+		ServletRequest filterRequest = mockFilterChain.getRequest();
+		ByteBuffer buffer = ByteBuffer.allocate(1024);
+
+		ReadableByteChannel readableByteChannel = Channels.newChannel(filterRequest.getInputStream());
+		IOUtils.read(readableByteChannel, buffer);
+		buffer.flip();
+		assertThat(content.length).isEqualTo(buffer.remaining());
+
+	}
+
+}