add default name for jar

Author: todd5167

core/src/main/java/com/dtstack/flink/sql/util/PluginUtil.java

@@ -158,8 +158,11 @@ public boolean accept(File dir, String name) {
             if (jarFiles != null && jarFiles.length > 0){
                 coreJarFileName = jarFiles[0].getName();
             }
+        }else {
+            coreJarFileName = prefix.toLowerCase() + ".jar";
         }
 
+
         return coreJarFileName;
     }