update gateway mvc post, put, and patch request body not required.

spring-cloud-gateway-mvc/src/main/java/org/springframework/cloud/gateway/mvc/ProxyExchange.java

@@ -453,7 +453,7 @@ public class ProxyExchange<T> {
 
 	protected static class BodyGrabber {
 
-		public Object body(@RequestBody Object body) {
+		public Object body(@RequestBody(required = false) Object body) {
 			return body;
 		}
 

spring-cloud-gateway-mvc/src/test/java/org/springframework/cloud/gateway/mvc/ProductionConfigurationTests.java

@@ -235,6 +235,12 @@ public class ProductionConfigurationTests {
 						.isEqualTo("host=localhost;foobar");
 	}
 
+	@Test
+	public void noBody() throws Exception {
+		Foo foo = rest.postForObject("/proxy/no-body", null, Foo.class);
+		assertThat(foo.getName()).isEqualTo("hello");
+	}
+
 	@Test
 	@SuppressWarnings({ "Duplicates", "unchecked" })
 	public void headers() throws Exception {
@@ -351,6 +357,12 @@ public class ProductionConfigurationTests {
 								.body(response.getBody().iterator().next()));
 			}
 
+			@PostMapping("/proxy/no-body")
+			public ResponseEntity<Foo> noBody(ProxyExchange<Foo> proxy) throws Exception {
+				return proxy.uri(home.toString() + "/foos")
+						.post();
+			}
+
 			@GetMapping("/forward/**")
 			public void forward(ProxyExchange<?> proxy) throws Exception {
 				String path = proxy.path("/forward");
@@ -413,6 +425,11 @@ public class ProductionConfigurationTests {
 				return Arrays.asList(new Foo("hello"));
 			}
 
+			@PostMapping("/foos")
+			public Foo postFoos() {
+				return new Foo("hello");
+			}
+
 			@GetMapping("/foos/{id}")
 			public Foo foo(@PathVariable Integer id, @RequestHeader HttpHeaders headers) {
 				String custom = headers.getFirst("X-Custom");