[UNDERTOW-2022] At MultipartParser.MultipartUploadHandler.close, clear the references to temp file handles

Signed-off-by: Flavia Rainone <[email protected]>

Author: fl4via

core/src/main/java/io/undertow/server/handlers/form/MultiPartParserDefinition.java

@@ -372,7 +372,6 @@ public void endPart() {
             }
         }
 
-
         public List<Path> getCreatedFiles() {
             return createdFiles;
         }
@@ -395,6 +394,7 @@ public void run() {
                             }
                         }
                     }
+                    files.clear();
                 }
             });