code: public void setStateBackend(StateBackend backend) {
  		if (backend != null) {
  			try {
  				InstantiationUtil.writeObjectToConfig(backend, this.config, STATE_BACKEND);
  			} catch (Exception e) {
  				throw new StreamTaskException("Could not serialize stateHandle provider.", e);
  			}
  		}
  	}
docs: ------------------------------------------------------------------------