public boolean hasTombstoneTtl() {
      return ((bitField0_ & 0x00000200) != 0);
    }
<pre>
The task tombstone time to live (TTL).

After a task is deleted or completed, the task's tombstone is
retained for the length of time specified by `tombstone_ttl`.
The tombstone is used by task de-duplication; another task with the same
name can't be created until the tombstone has expired. For more information
about task de-duplication, see the documentation for
[CreateTaskRequest][google.cloud.tasks.v2beta2.CreateTaskRequest.task].

Queues created by Cloud Tasks have a default `tombstone_ttl` of 1 hour.
</pre>

<code>.google.protobuf.Duration tombstone_ttl = 10;</code>

@return Whether the tombstoneTtl field is set.
java-tasks/proto-google-cloud-tasks-v2beta2/src/main/java/com/google/cloud/tasks/v2beta2/Queue.java