code: protected Long launchProcess(Long processId, Long eventInstId, String masterRequestId,
              Map<String,Object> parameters, Map<String,String> headers) throws Exception {
          Map<String,String> stringParams = translateParameters(processId, parameters);
          ProcessEngineDriver driver = new ProcessEngineDriver();
          return driver.startProcess(processId, masterRequestId, OwnerType.DOCUMENT, eventInstId, stringParams, headers);
      }
docs: This method is used to start a regular process.
  You should use invokeProcessAsService for invoking service processes.
  Documents must be passed as DocumentReferences.
  @see {@link #invokeProcess(Long, Long, String, Map<String,String>)}
  
  @param processId Process definition ID of the process
  @param eventInstId The ID of the external message triggering the handler
  @param masterRequestId Master request ID to be assigned to the process instance
  @param parameters Input parameter bindings for the process instance to be created
  @param headers request headers