Merge pull request #1934 from tomzhang170/tomzhang170-patch-1

Update TriggerCallbackThread.java

xxl-job-core/src/main/java/com/xxl/job/core/thread/TriggerCallbackThread.java

@@ -241,6 +241,9 @@ public class TriggerCallbackThread {
         // load and clear file, retry
         for (File callbaclLogFile: callbackLogPath.listFiles()) {
             byte[] callbackParamList_bytes = FileUtil.readFileContent(callbaclLogFile);
+            if(callbackParamList_bytes == null || callbackParamList_bytes.length < 1){
+                continue;
+            }
             List<HandleCallbackParam> callbackParamList = (List<HandleCallbackParam>) JdkSerializeTool.deserialize(callbackParamList_bytes, List.class);
 
             callbaclLogFile.delete();