Fix: Return correct ByteArrayInputStream object instead of null in some cases

Author: ashinnotfound

spring-cloud-gateway-server-mvc/src/main/java/org/springframework/cloud/gateway/server/mvc/common/MvcUtils.java

@@ -109,6 +109,10 @@ public static ByteArrayInputStream cacheBody(ServerRequest request) {
 			}
 			else {
 				body = getAttribute(request, CACHED_REQUEST_BODY_ATTR);
+				if (body == null) {
+					body = new ByteArrayInputStream(bytes);
+					putAttribute(request, MvcUtils.CACHED_REQUEST_BODY_ATTR, body);
+				}
 			}
 			return body;
 		}