public Builder setOldestEstimatedArrivalTime(
        com.google.protobuf.Timestamp.Builder builderForValue) {
      if (oldestEstimatedArrivalTimeBuilder_ == null) {
        oldestEstimatedArrivalTime_ = builderForValue.build();
      } else {
        oldestEstimatedArrivalTimeBuilder_.setMessage(builderForValue.build());
      }
      bitField0_ |= 0x00000002;
      onChanged();
      return this;
    }
<pre>
Output only. An estimation of the nearest time in the future where a task
in the queue is scheduled to be executed.
</pre>

<code>
.google.protobuf.Timestamp oldest_estimated_arrival_time = 2 [(.google.api.field_behavior) = OUTPUT_ONLY];
</code>
java-tasks/proto-google-cloud-tasks-v2beta3/src/main/java/com/google/cloud/tasks/v2beta3/QueueStats.java