code: public final void registerExecutionType(ExecutionType executionType) {
  	if (executionType == null) {
  	  throw new TaskExeception(ExecutionType.class.getSimpleName() + " NULL");
  	}
  	this.executionType = executionType;
    }
docs: Registers the executor type. DO NOT USE THIS METHOD UNLESS YOU ARE
  DEVELOPING A NEW TASK EXECUTOR.
  
  @param executionType
  the executor type