Gremlin console not connecting to Neo4J

Question

I am new to Apache TinkerPop and Gremlin. I am trying to connect a gremlin console to a Neo4J server.

I installed neo4j-gremlin dependency in gremlin console using the following command:

gremlin> :install com.tinkerpop neo4j-gremlin 3.0.0.M7

It was installed successfully.

When I run the following command to connect to the Ne04J server, I get an exception:

gremlin> g = new Neo4jGraph('/tmp/neo4j');

Exception:

java.lang.NullPointerException
at java.util.concurrent.ConcurrentHashMap.replaceNode(ConcurrentHashMap.java:1106)
at java.util.concurrent.ConcurrentHashMap.remove(ConcurrentHashMap.java:1097)
at org.codehaus.groovy.runtime.memoize.UnlimitedConcurrentCache.remove(UnlimitedConcurrentCache.java:70)
at groovy.lang.GroovyClassLoader.removeClassCacheEntry(GroovyClassLoader.java:676)
at sun.reflect.GeneratedMethodAccessor27.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.runtime.callsite.PlainObjectMetaMethodSite.doInvoke(PlainObjectMetaMethodSite.java:43)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite$PojoCachedMethodSiteNoUnwrapNoCoerce.invoke(PojoMetaMethodSite.java:211)
at org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:53)
at org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:47)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:115)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:127)
at org.codehaus.groovy.tools.shell.Interpreter.evaluate(Interpreter.groovy:98)
at org.codehaus.groovy.tools.shell.Evaluator$evaluate.call(Unknown Source)
at org.codehaus.groovy.tools.shell.Groovysh.execute(Groovysh.groovy:201)
at org.apache.tinkerpop.gremlin.console.GremlinGroovysh.super$3$execute(GremlinGroovysh.groovy)
at sun.reflect.GeneratedMethodAccessor22.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:144)
at org.apache.tinkerpop.gremlin.console.GremlinGroovysh.execute(GremlinGroovysh.groovy:83)
at org.codehaus.groovy.tools.shell.Shell.leftShift(Shell.groovy:120)
at org.codehaus.groovy.tools.shell.Shell$leftShift$1.call(Unknown Source)
at org.codehaus.groovy.tools.shell.ShellRunner.work(ShellRunner.groovy:93)
at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$work(InteractiveShellRunner.groovy)
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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:144)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0(ScriptBytecodeAdapter.java:164)
at org.codehaus.groovy.tools.shell.InteractiveShellRunner.work(InteractiveShellRunner.groovy:138)
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.codehaus.groovy.runtime.callsite.PlainObjectMetaMethodSite.doInvoke(PlainObjectMetaMethodSite.java:43)
at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite$PogoCachedMethodSiteNoUnwrapNoCoerce.invoke(PogoMetaMethodSite.java:190)
at org.codehaus.groovy.runtime.callsite.PogoMetaMethodSite.callCurrent(PogoMetaMethodSite.java:58)
at org.codehaus.groovy.runtime.callsite.AbstractCallSite.callCurrent(AbstractCallSite.java:160)
at org.codehaus.groovy.tools.shell.ShellRunner.run(ShellRunner.groovy:57)
at org.codehaus.groovy.tools.shell.InteractiveShellRunner.super$2$run(InteractiveShellRunner.groovy)
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.codehaus.groovy.reflection.CachedMethod.invoke(CachedMethod.java:101)
at groovy.lang.MetaMethod.doMethodInvoke(MetaMethod.java:323)
at groovy.lang.MetaClassImpl.invokeMethod(MetaClassImpl.java:1217)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuperN(ScriptBytecodeAdapter.java:144)
at org.codehaus.groovy.runtime.ScriptBytecodeAdapter.invokeMethodOnSuper0(ScriptBytecodeAdapter.java:164)
at org.codehaus.groovy.tools.shell.InteractiveShellRunner.run(InteractiveShellRunner.groovy:97)
at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:234)
at org.apache.tinkerpop.gremlin.console.Console.<init>(Console.groovy:168)
at org.codehaus.groovy.vmplugin.v7.IndyInterface.selectMethod(IndyInterface.java:234)
at org.apache.tinkerpop.gremlin.console.Console.main(Console.groovy:502)

If anybody knows what I am doing wrong, kindly help.

I am using a Mac.