code: def share_pull_request(self, user_message, repository_id, pull_request_id, project=None):
          
          route_values = {}
          if project is not None:
              route_values['project'] = self._serialize.url('project', project, 'str')
          if repository_id is not None:
              route_values['repositoryId'] = self._serialize.url('repository_id', repository_id, 'str')
          if pull_request_id is not None:
              route_values['pullRequestId'] = self._serialize.url('pull_request_id', pull_request_id, 'int')
          content = self._serialize.body(user_message, 'ShareNotificationContext')
          self._send(http_method='POST',
                     location_id='696f3a82-47c9-487f-9117-b9d00972ca84',
                     version='5.0-preview.1',
                     route_values=route_values,
                     content=content)
docs: SharePullRequest.
          [Preview API] Sends an e-mail notification about a specific pull request to a set of recipients
          :param :class:`<ShareNotificationContext> <azure.devops.v5_0.git.models.ShareNotificationContext>` user_message:
          :param str repository_id: ID of the git repository.
          :param int pull_request_id: ID of the pull request.
          :param str project: Project ID or project name