code: def _injectWorkerFiles(self, node, botoExists):
          
          node.waitForNode('toil_worker', keyName=self._keyName)
          node.copySshKeys(self._keyName)
          node.injectFile(self._credentialsPath, GoogleJobStore.nodeServiceAccountJson, 'toil_worker')
          if self._sseKey:
              node.injectFile(self._sseKey, self._sseKey, 'toil_worker')
          if botoExists:
              node.injectFile(self._botoPath, self.NODE_BOTO_PATH, 'toil_worker')
docs: Set up the credentials on the worker.