Request message for ListQueues.
Required. The location name. For example: ``projects/PROJECT_ID/locations/LOCATION_ID``
``filter`` can be used to specify a subset of queues. Any Queue field can be used as a filter and several operators as supported. For example: ``<=,><,>=, >, !=, =, :``. The filter syntax is the same as described in `Stackdriver's Advanced Logs Filters
Requested page size. The maximum page size is 9800. If unspecified, the page size will be the maximum. Fewer queues than requested might be returned, even if more queues exist; use the next_page_token in the response to determine if more queues exist.
A token identifying the page of results to return. To request the first page results, page_token must be empty. To request the next page of results, page_token must be the value of next_page_token returned from the previous call to ListQueues method. It is an error to switch the value of the filter while iterating through pages.
Optional. Read mask is used for a more granular control over what the API returns. If the mask is not present all fields will be returned except [Queue.stats]. [Queue.stats] will be returned only if it was explicitly specified in the mask.