list method
Returns the list of all contexts in the specified session.
Request parameters:
parent - Required. The session to list all contexts from. Format:
projects//agent/sessions/ or
projects//agent/environments//users//sessions/. If Environment ID is
not specified, we assume default 'draft' environment. If User ID is not
specified, we assume default '-' user.
Value must have pattern ^projects/\[^/\]+/agent/sessions/\[^/\]+$.
pageSize - Optional. The maximum number of items to return in a single
page. By default 100 and at most 1000.
pageToken - Optional. The next_page_token value returned from a previous
list request.
$fields - Selector specifying which fields to include in a partial
response.
Completes with a GoogleCloudDialogflowV2ListContextsResponse.
Completes with a commons.ApiRequestError if the API endpoint returned an error.
If the used http.Client completes with an error when making a REST call,
this method will complete with the same error.
Implementation
async.Future<GoogleCloudDialogflowV2ListContextsResponse> list(
  core.String parent, {
  core.int? pageSize,
  core.String? pageToken,
  core.String? $fields,
}) async {
  final queryParams_ = <core.String, core.List<core.String>>{
    if (pageSize != null) 'pageSize': ['${pageSize}'],
    if (pageToken != null) 'pageToken': [pageToken],
    if ($fields != null) 'fields': [$fields],
  };
  final url_ = 'v2/' + core.Uri.encodeFull('$parent') + '/contexts';
  final response_ = await _requester.request(
    url_,
    'GET',
    queryParams: queryParams_,
  );
  return GoogleCloudDialogflowV2ListContextsResponse.fromJson(
      response_ as core.Map<core.String, core.dynamic>);
}