NPE with test HasTest.g_V_hasIdXwithinXemptyXX_count()

error with test HasTest.g_V_hasIdXwithinXemptyXX_count():
```
java.lang.NullPointerException
at org.apache.tinkerpop.gremlin.process.traversal.step.map.GraphStep.hashCode(GraphStep.java:176)
at com.baidu.hugegraph.traversal.optimize.HugeGraphStep.hashCode(HugeGraphStep.java:204)
at org.apache.tinkerpop.gremlin.process.traversal.step.util.AbstractStep.equals(AbstractStep.java:192)
at org.apache.tinkerpop.gremlin.process.traversal.Step.equals(Step.java:173)
at org.apache.tinkerpop.gremlin.process.traversal.util.TraversalHelper.stepIndex(TraversalHelper.java:229)
at org.apache.tinkerpop.gremlin.process.traversal.Traversal$Admin.removeStep(Traversal.java:379)
at com.baidu.hugegraph.traversal.optimize.HugeCountStepStrategy.apply(HugeCountStepStrategy.java:106)
at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversalStrategies.applyStrategies(DefaultTraversalStrategies.java:84)
at org.apache.tinkerpop.gremlin.process.traversal.util.DefaultTraversal.applyStrategies(DefaultTraversal.java:124)
at org.apache.tinkerpop.gremlin.AbstractGremlinTest.printTraversalForm(AbstractGremlinTest.java:278)
at org.apache.tinkerpop.gremlin.process.traversal.step.filter.HasTest.g_V_hasIdXwithinXemptyXX_count(HasTest.java:518)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
at org.junit.internal.runners.statements.RunAfters.evaluate(RunAfters.java:27)
at org.junit.rules.TestWatcher$1.evaluate(TestWatcher.java:55)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)
at org.apache.tinkerpop.gremlin.process.GremlinProcessRunner.runChild(GremlinProcessRunner.java:53)
at org.apache.tinkerpop.gremlin.process.GremlinProcessRunner.runChild(GremlinProcessRunner.java:37)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.apache.tinkerpop.gremlin.AbstractGremlinSuite.runChild(AbstractGremlinSuite.java:229)
at org.apache.tinkerpop.gremlin.AbstractGremlinSuite.runChild(AbstractGremlinSuite.java:51)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at com.baidu.hugegraph.tinkerpop.ProcessBasicSuite$1.evaluate(ProcessBasicSuite.java:293)
at org.apache.tinkerpop.gremlin.AbstractGremlinSuite$1.evaluate(AbstractGremlinSuite.java:238)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

```
set `GraphStep.ids=null` GraphStep.addIds(Object... newIds)
```
Thread [main] (Suspended (breakpoint at line 119 in GraphStep))
HugeGraphStep(GraphStep).addIds(Object...) line: 119
GraphStep.processHasContainerIds(GraphStep, HasContainer) line: 202
TraversalUtil.extractHasContainer(HugeGraphStep, Admin) line: 104
HugeGraphStepStrategy.apply(Admin) line: 60
DefaultTraversalStrategies.applyStrategies(Admin) line: 84
DefaultGraphTraversal(DefaultTraversal).applyStrategies() line: 124
HasTest$Traversals(AbstractGremlinTest).printTraversalForm(Traversal) line: 278
HasTest$Traversals(HasTest).g_V_hasIdXwithinXemptyXX_count() line: 518
NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]
NativeMethodAccessorImpl.invoke(Object, Object[]) line: 62
DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 43
Method.invoke(Object, Object...) line: 498
FrameworkMethod$1.runReflectiveCall() line: 50
FrameworkMethod$1(ReflectiveCallable).run() line: 12
FrameworkMethod.invokeExplosively(Object, Object...) line: 47
InvokeMethod.evaluate() line: 17
RunBefores.evaluate() line: 26
RunAfters.evaluate() line: 27
TestWatcher$1.evaluate() line: 55
RunRules.evaluate() line: 20
GremlinProcessRunner.runChild(FrameworkMethod, RunNotifier) line: 53
GremlinProcessRunner.runChild(Object, RunNotifier) line: 37
ParentRunner$3.run() line: 290
ParentRunner$1.schedule(Runnable) line: 71
GremlinProcessRunner(ParentRunner).runChildren(RunNotifier) line: 288
ParentRunner.access$000(ParentRunner, RunNotifier) line: 58
ParentRunner$2.evaluate() line: 268
GremlinProcessRunner(ParentRunner).run(RunNotifier) line: 363
ProcessBasicSuite(Suite).runChild(Runner, RunNotifier) line: 128
ProcessBasicSuite(AbstractGremlinSuite).runChild(Runner, RunNotifier) line: 229
ProcessBasicSuite(AbstractGremlinSuite).runChild(Object, RunNotifier) line: 51
ParentRunner$3.run() line: 290
ParentRunner$1.schedule(Runnable) line: 71
ProcessBasicSuite(ParentRunner).runChildren(RunNotifier) line: 288
ParentRunner.access$000(ParentRunner, RunNotifier) line: 58
ParentRunner$2.evaluate() line: 268
ProcessBasicSuite$1.evaluate() line: 293
AbstractGremlinSuite$1.evaluate() line: 238
ProcessBasicSuite(ParentRunner).run(RunNotifier) line: 363
JUnit4TestReference.run(TestExecution) line: 86
TestExecution.run(ITestReference[]) line: 38
RemoteTestRunner.runTests(String[], String, TestExecution) line: 459
RemoteTestRunner.runTests(TestExecution) line: 678
RemoteTestRunner.run() line: 382
RemoteTestRunner.main(String[]) line: 192

```