Calling a process block multiple times from within a script.

I have the following function setup in a script :

JSONObject getVmwareApiOutput(String apiUrl, String vCenterSessionToken){
    ExecuteSuperProcess getVmwareApi = new ExecuteSuperProcess();
           getVmwareApi.processBlock = WorkflowElement.parse("<processBlock>pbGetVmwareApi</processBlock>");
    getVmwareApi.inputs      = WorkflowElement.parse("<inputs><url>" + apiUrl + "</url><vmware-api-session-id>" + vCenterSessionToken + "</vmware-api-session-id></inputs>");
    getVmwareApi.execute(workflow);
    JSONObject vmWareApiOutput = new JSONObject(xpath:{/workflow/variables/restCallOutPut}.replace("[","").replace("]",""));
return vmWareApiOutput;
}

This works fine the first time I call the script.

But subsequents calls result in the following:

9908 ExecuteSuperProcess     : [Search vCenters for Virtual Machines (scrSearchForVirtualMachine)] process block for super process id [9321], has already completed
9908 ExecuteSuperProcess     : [Search vCenters for Virtual Machines (scrSearchForVirtualMachine)] process block for super process id [9321], has already completed
9908 ExecuteSuperProcess     : [Search vCenters for Virtual Machines (scrSearchForVirtualMachine)] process block for super process id [9321], has already completed