When submodules are enabled with jGit building gives:

FATAL: not implemented yet
java.lang.UnsupportedOperationException: not implemented yet
at org.jenkinsci.plugins.gitclient.JGitAPIImpl.setupSubmoduleUrls(JGitAPIImpl.java:2125)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:622)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.perform(RemoteInvocationHandler.java:326)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:301)
at hudson.remoting.RemoteInvocationHandler$RPCRequest.call(RemoteInvocationHandler.java:260)
at hudson.remoting.UserRequest.perform(UserRequest.java:121)
at hudson.remoting.UserRequest.perform(UserRequest.java:49)
at hudson.remoting.Request$2.run(Request.java:324)
at hudson.remoting.InterceptingExecutorService$1.call(InterceptingExecutorService.java:68)
at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:334)
at java.util.concurrent.FutureTask.run(FutureTask.java:166)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1146)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
at java.lang.Thread.run(Thread.java:701)
at ......remote call to b4531083cc3f@we13196(Native Method)
at hudson.remoting.Channel.attachCallSiteStackTrace(Channel.java:1356)
at hudson.remoting.UserResponse.retrieve(UserRequest.java:221)
at hudson.remoting.Channel.call(Channel.java:752)
at hudson.remoting.RemoteInvocationHandler.invoke(RemoteInvocationHandler.java:179)
at com.sun.proxy.$Proxy100.setupSubmoduleUrls(Unknown Source)
at org.jenkinsci.plugins.gitclient.RemoteGitImpl.setupSubmoduleUrls(RemoteGitImpl.java:477)
at hudson.plugins.git.extensions.impl.SubmoduleOption.onCheckoutCompleted(SubmoduleOption.java:82)
at hudson.plugins.git.GitSCM.checkout(GitSCM.java:1006)
at hudson.scm.SCM.checkout(SCM.java:484)
at hudson.model.AbstractProject.checkout(AbstractProject.java:1265)
at hudson.model.AbstractBuild$AbstractBuildExecution.defaultCheckout(AbstractBuild.java:622)
at jenkins.scm.SCMCheckoutStrategy.checkout(SCMCheckoutStrategy.java:86)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:528)
at hudson.model.Run.execute(Run.java:1759)
at hudson.maven.MavenModuleSetBuild.run(MavenModuleSetBuild.java:531)
at hudson.model.ResourceController.execute(ResourceController.java:89)
at hudson.model.Executor.run(Executor.java:240)