prepare for ap algo

[javeme]

Change-Id: Ic0ea69b80a49d0e5da04e862d102f78e89bcf86e

[javeme]

[codecov]

Codecov Report

Merging #921 into master will decrease coverage by 0.20%.
The diff coverage is 73.04%.

@@             Coverage Diff              @@
##             master     #921      +/-   ##
============================================
- Coverage     72.30%   72.10%   -0.21%     
- Complexity     4511     4595      +84     
============================================
  Files           287      290       +3     
  Lines         21464    21876     +412     
  Branches       3040     3095      +55     
============================================
+ Hits          15520    15774     +254     
- Misses         4428     4553     +125     
- Partials       1516     1549      +33     

Impacted Files	Coverage Δ	Complexity Δ
...baidu/hugegraph/backend/store/BackendMutation.java	82.56% <0.00%> (-3.15%)	32.00 <0.00> (ø)
...ore/src/main/java/com/baidu/hugegraph/job/Job.java	63.88% <0.00%> (-7.99%)	8.00 <0.00> (ø)
...java/com/baidu/hugegraph/schema/SchemaElement.java	77.96% <0.00%> (-1.35%)	26.00 <1.00> (ø)
...c/main/java/com/baidu/hugegraph/task/HugeTask.java	70.38% <0.00%> (-0.94%)	65.00 <0.00> (ø)
...du/hugegraph/backend/tx/GraphIndexTransaction.java	79.45% <14.28%> (-0.57%)	186.00 <0.00> (ø)
...c/main/java/com/baidu/hugegraph/util/JsonUtil.java	62.71% <27.27%> (-8.13%)	8.00 <0.00> (ø)
...c/main/java/com/baidu/hugegraph/HugeException.java	86.66% <50.00%> (-5.65%)	7.00 <1.00> (+1.00)	⬇️
...ain/java/com/baidu/hugegraph/schema/EdgeLabel.java	80.64% <50.00%> (+2.86%)	16.00 <4.00> (+2.00)
...ava/com/baidu/hugegraph/structure/HugeElement.java	68.66% <50.00%> (+1.09%)	52.00 <1.00> (+2.00)
...idu/hugegraph/backend/tx/IndexableTransaction.java	85.18% <66.66%> (ø)	15.00 <0.00> (ø)
... and 59 more

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[zhoney]

add empty after "if"

[javeme]

pg ci error:

[ERROR] Tests run: 588, Failures: 0, Errors: 1, Skipped: 28, Time elapsed: 72.951 s <<< FAILURE! - in com.baidu.hugegraph.core.CoreTestSuite
[ERROR] testTask(com.baidu.hugegraph.core.TaskCoreTest)  Time elapsed: 1.2 s  <<< ERROR!
com.baidu.hugegraph.exception.NotFoundException: Can't find task with id '88888'
	at com.baidu.hugegraph.core.TaskCoreTest.testTask(TaskCoreTest.java:105)