Change the import order, and use HttpHeaders.

Signed-off-by: Mengqi Xu <2663479778@qq.com>

spring-webmvc/src/main/java/org/springframework/web/servlet/mvc/method/annotation/HttpEntityMethodProcessor.java

@@ -31,11 +31,11 @@
 
 import org.springframework.core.MethodParameter;
 import org.springframework.core.ResolvableType;
-import org.springframework.http.HttpStatusCode;
-import org.springframework.http.HttpStatus;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.HttpStatusCode;
 import org.springframework.http.ProblemDetail;
 import org.springframework.http.RequestEntity;
 import org.springframework.http.ResponseEntity;
@@ -250,7 +250,7 @@ && isResourceNotModified(inputMessage, outputMessage)) {
 				}
 			}
 			else if (httpStatusCode.is3xxRedirection()) {
-				String location = outputHeaders.getFirst("location");
+				String location = outputHeaders.getFirst(HttpHeaders.LOCATION);
 				if (location != null) {
 					saveFlashAttributes(mavContainer, webRequest, location);
 				}