Setting global variable over BPM Remote API ends in error

Issue

Setting a global variable over the remote api:

    RemoteRestRuntimeEngineFactory restSessionFactory
         = new RemoteRestRuntimeEngineFactory(deploymentId, deploymentUrl, user, password);
    RuntimeEngine engine = restSessionFactory.newRuntimeEngine();
    KieSession ksession = engine.getKieSession();
    ProcessInstance processInstance = ksession.startProcess("sampleProcess");
    String res = (String)ksession.getGlobal("response");              
    System.out.println("RES: "+res);

Fails with:

Exception in thread "main" org.jboss.resteasy.client.ClientResponseFailure: Unable to find a MessageBodyReader of content-type application/xml and type null
    at org.jboss.resteasy.client.core.BaseClientResponse.createResponseFailure(BaseClientResponse.java:523)
    at org.jboss.resteasy.client.core.BaseClientResponse.createResponseFailure(BaseClientResponse.java:514)
    at org.jboss.resteasy.client.core.BaseClientResponse.readFrom(BaseClientResponse.java:415)
    at org.jboss.resteasy.client.core.BaseClientResponse.getEntity(BaseClientResponse.java:377)
    at org.jboss.resteasy.client.core.BaseClientResponse.getEntity(BaseClientResponse.java:350)
    at org.jboss.resteasy.client.core.BaseClientResponse.getEntity(BaseClientResponse.java:344)
    at org.kie.services.client.api.command.AbstractRemoteCommandObject.executeRestCommand(AbstractRemoteCommandObject.java:410)
    at org.kie.services.client.api.command.AbstractRemoteCommandObject.execute(AbstractRemoteCommandObject.java:124)
    at org.drools.core.command.impl.CommandBasedStatefulKnowledgeSession.startProcess(CommandBasedStatefulKnowledgeSession.java:232)
    at com.test.TestRemoteBPMClient.test(TestRemoteBPMClient.java:36)
    at com.test.TestRemoteBPMClient.main(TestRemoteBPMClient.java:18)

How to correctly implement this requirement?