def _get_credentials(self):
        """
        
        """
        key_path = self._get_field('key_path', False)
        keyfile_dict = self._get_field('keyfile_dict', False)
        scope = self._get_field('scope', None)
        if scope:
            scopes = [s.strip() for s in scope.split(',')]
        else:
            scopes = _DEFAULT_SCOPES

        if not key_path and not keyfile_dict:
            self.log.info('Getting connection using `google.auth.default()` '
                          'since no key file is defined for hook.')
            credentials, _ = google.auth.default(scopes=scopes)
        elif key_path:
            # Get credentials from a JSON file.
            if key_path.endswith('.json'):
                self.log.debug('Getting connection using JSON key file %s' % key_path)
                credentials = (
                    google.oauth2.service_account.Credentials.from_service_account_file(
                        key_path, scopes=scopes)
                )
            elif key_path.endswith('.p12'):
                raise AirflowException('Legacy P12 key file are not supported, '
                                       'use a JSON key file.')
            else:
                raise AirflowException('Unrecognised extension for key file.')
        else:
            # Get credentials from JSON data provided in the UI.
            try:
                keyfile_dict = json.loads(keyfile_dict)

                # Depending on how the JSON was formatted, it may contain
                # escaped newlines. Convert those to actual newlines.
                keyfile_dict['private_key'] = keyfile_dict['private_key'].replace(
                    '\\n', '\n')

                credentials = (
                    google.oauth2.service_account.Credentials.from_service_account_info(
                        keyfile_dict, scopes=scopes)
                )
            except json.decoder.JSONDecodeError:
                raise AirflowException('Invalid key JSON.')

        return credentials.with_subject(self.delegate_to) \
            if self.delegate_to else credentials