transport/https-sample - [WARNING] Couldn't destroy threadgroup org.codehaus.mojo.exec.ExecJavaMojo$IsolatedThreadGroup[name=org.apache.axis2.examples.httpsclient.SimpleServiceClient,maxpri=10]

I am following samples/transport/https-sample/README.txt.

Running the Sample Client get the expected result.

However, how to fix the following WARNING?
org.apache.axis2.deployment.AxisConfigBuilder processDeployers
WARNING: Unable to instantiate deployer
org.apache.axis2.deployment.ServiceDeployer; see debug logs for more details
<ns:helloServiceResponse xmlns:ns="
http://httpsservice.examples.axis2.apache.org"><ns:return>Hello World
</ns:return></ns:helloServiceResponse>[WARNING] thread
Thread[MultiThreadedHttpConnectionManager
cleanup,5,org.apache.axis2.examples.httpsclient.SimpleServiceClient] was
interrupted but is still alive after waiting at least 14999msecs
[WARNING] thread Thread[MultiThreadedHttpConnectionManager
cleanup,5,org.apache.axis2.examples.httpsclient.SimpleServiceClient] will
linger despite being asked to die via interruption
[WARNING] NOTE: 1 thread(s) did not finish despite being asked to  via
interruption. This is not a problem with exec:java, it is a problem with
the running code. Although not serious, it should be remedied.
[WARNING] Couldn't destroy threadgroup
org.codehaus.mojo.exec.ExecJavaMojo$IsolatedThreadGroup[name=org.apache.axis2.examples.httpsclient.SimpleServiceClient,maxpri=10]
java.lang.IllegalThreadStateException
    at java.lang.ThreadGroup.destroy (ThreadGroup.java:778)
    at org.codehaus.mojo.exec.ExecJavaMojo.execute (ExecJavaMojo.java:321)
    at org.apache.maven.plugin.DefaultBuildPluginManager.executeMojo
(DefaultBuildPluginManager.java:137)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute
(MojoExecutor.java:210)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute
(MojoExecutor.java:156)
    at org.apache.maven.lifecycle.internal.MojoExecutor.execute
(MojoExecutor.java:148)
    at
org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject
(LifecycleModuleBuilder.java:117)
    at
org.apache.maven.lifecycle.internal.LifecycleModuleBuilder.buildProject
(LifecycleModuleBuilder.java:81)
    at
org.apache.maven.lifecycle.internal.builder.singlethreaded.SingleThreadedBuilder.build
(SingleThreadedBuilder.java:56)
    at org.apache.maven.lifecycle.internal.LifecycleStarter.execute
(LifecycleStarter.java:128)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:305)
    at org.apache.maven.DefaultMaven.doExecute (DefaultMaven.java:192)
    at org.apache.maven.DefaultMaven.execute (DefaultMaven.java:105)
    at org.apache.maven.cli.MavenCli.execute (MavenCli.java:956)
    at org.apache.maven.cli.MavenCli.doMain (MavenCli.java:288)
    at org.apache.maven.cli.MavenCli.main (MavenCli.java:192)
    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.plexus.classworlds.launcher.Launcher.launchEnhanced
(Launcher.java:289)
    at org.codehaus.plexus.classworlds.launcher.Launcher.launch
(Launcher.java:229)
    at org.codehaus.plexus.classworlds.launcher.Launcher.mainWithExitCode
(Launcher.java:415)
    at org.codehaus.plexus.classworlds.launcher.Launcher.main
(Launcher.java:356)