public Builder setUpdateMask(com.google.protobuf.FieldMask value) {
      if (updateMaskBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        updateMask_ = value;
      } else {
        updateMaskBuilder_.setMessage(value);
      }
      bitField0_ |= 0x00000002;
      onChanged();
      return this;
    }
<pre>
Optional. Required. The field to update.

You can update one of the following fields in a subscription:

* [`expire_time`][google.apps.events.subscriptions.v1.Subscription.expire_time]: The timestamp when the
  subscription expires.
* [`ttl`][google.apps.events.subscriptions.v1.Subscription.ttl]: The
time-to-live (TTL) or duration of the
  subscription.
</pre>

<code>.google.protobuf.FieldMask update_mask = 2 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-workspaceevents/proto-google-cloud-workspaceevents-v1/src/main/java/com/google/apps/events/subscriptions/v1/UpdateSubscriptionRequest.java