chore(cloudiot): update the api

#### cloudiot:v1

The following keys were changed:
- resources.projects.resources.locations.resources.registries.resources.devices.methods.get.parameters.fieldMask (Total Keys: 1)
- resources.projects.resources.locations.resources.registries.resources.devices.methods.list.parameters.fieldMask (Total Keys: 1)
- resources.projects.resources.locations.resources.registries.resources.groups.resources.devices.methods.list.parameters.fieldMask (Total Keys: 1)
- revision (Total Keys: 1)

docs/dyn/cloudiot_v1.projects.locations.registries.devices.html

@@ -261,7 +261,7 @@ <h3>Method Details</h3>
 
 Args:
   name: string, Required. The name of the device. For example, `projects/p0/locations/us-central1/registries/registry0/devices/device0` or `projects/p0/locations/us-central1/registries/registry0/devices/{num_id}`. (required)
-  fieldMask: string, The fields of the `Device` resource to be returned in the response. If the field mask is unset or empty, all fields are returned.
+  fieldMask: string, The fields of the `Device` resource to be returned in the response. If the field mask is unset or empty, all fields are returned. Fields have to be provided in snake_case format, for example: `last_heartbeat_time`.
   x__xgafv: string, V1 error format.
     Allowed values
       1 - v1 error format
@@ -330,7 +330,7 @@ <h3>Method Details</h3>
   parent: string, Required. The device registry path. Required. For example, `projects/my-project/locations/us-central1/registries/my-registry`. (required)
   deviceIds: string, A list of device string IDs. For example, `[&#x27;device0&#x27;, &#x27;device12&#x27;]`. If empty, this field is ignored. Maximum IDs: 10,000 (repeated)
   deviceNumIds: string, A list of device numeric IDs. If empty, this field is ignored. Maximum IDs: 10,000. (repeated)
-  fieldMask: string, The fields of the `Device` resource to be returned in the response. The fields `id` and `num_id` are always returned, along with any other fields specified.
+  fieldMask: string, The fields of the `Device` resource to be returned in the response. The fields `id` and `num_id` are always returned, along with any other fields specified in snake_case format, for example: `last_heartbeat_time`.
   gatewayListOptions_associationsDeviceId: string, If set, returns only the gateways with which the specified device is associated. The device ID can be numeric (`num_id`) or the user-defined string (`id`). For example, if `456` is specified, returns only the gateways to which the device with `num_id` 456 is bound.
   gatewayListOptions_associationsGatewayId: string, If set, only devices associated with the specified gateway are returned. The gateway ID can be numeric (`num_id`) or the user-defined string (`id`). For example, if `123` is specified, only devices bound to the gateway with `num_id` 123 are returned.
   gatewayListOptions_gatewayType: string, If `GATEWAY` is specified, only gateways are returned. If `NON_GATEWAY` is specified, only non-gateway devices are returned. If `GATEWAY_TYPE_UNSPECIFIED` is specified, all devices are returned.

docs/dyn/cloudiot_v1.projects.locations.registries.groups.devices.html

@@ -97,7 +97,7 @@ <h3>Method Details</h3>
   parent: string, Required. The device registry path. Required. For example, `projects/my-project/locations/us-central1/registries/my-registry`. (required)
   deviceIds: string, A list of device string IDs. For example, `[&#x27;device0&#x27;, &#x27;device12&#x27;]`. If empty, this field is ignored. Maximum IDs: 10,000 (repeated)
   deviceNumIds: string, A list of device numeric IDs. If empty, this field is ignored. Maximum IDs: 10,000. (repeated)
-  fieldMask: string, The fields of the `Device` resource to be returned in the response. The fields `id` and `num_id` are always returned, along with any other fields specified.
+  fieldMask: string, The fields of the `Device` resource to be returned in the response. The fields `id` and `num_id` are always returned, along with any other fields specified in snake_case format, for example: `last_heartbeat_time`.
   gatewayListOptions_associationsDeviceId: string, If set, returns only the gateways with which the specified device is associated. The device ID can be numeric (`num_id`) or the user-defined string (`id`). For example, if `456` is specified, returns only the gateways to which the device with `num_id` 456 is bound.
   gatewayListOptions_associationsGatewayId: string, If set, only devices associated with the specified gateway are returned. The gateway ID can be numeric (`num_id`) or the user-defined string (`id`). For example, if `123` is specified, only devices bound to the gateway with `num_id` 123 are returned.
   gatewayListOptions_gatewayType: string, If `GATEWAY` is specified, only gateways are returned. If `NON_GATEWAY` is specified, only non-gateway devices are returned. If `GATEWAY_TYPE_UNSPECIFIED` is specified, all devices are returned.