private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort,
            com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort.Builder,
            com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffortOrBuilder>
        getBestEffortFieldBuilder() {
      if (bestEffortBuilder_ == null) {
        if (!(tierCase_ == 3)) {
          tier_ = com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort.getDefaultInstance();
        }
        bestEffortBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort,
                com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort.Builder,
                com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffortOrBuilder>(
                (com.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort) tier_,
                getParentForChildren(),
                isClean());
        tier_ = null;
      }
      tierCase_ = 3;
      onChanged();
      return bestEffortBuilder_;
    }
<pre>
The BestEffort tier.
</pre>

<code>.google.cloud.tpu.v2alpha1.QueuedResource.BestEffort best_effort = 3;</code>
java-tpu/proto-google-cloud-tpu-v2alpha1/src/main/java/com/google/cloud/tpu/v2alpha1/QueuedResource.java