private com.google.protobuf.SingleFieldBuilderV3<
              com.google.protobuf.Duration,
              com.google.protobuf.Duration.Builder,
              com.google.protobuf.DurationOrBuilder>
          getMinDurationFieldBuilder() {
        if (minDurationBuilder_ == null) {
          minDurationBuilder_ =
              new com.google.protobuf.SingleFieldBuilderV3<
                  com.google.protobuf.Duration,
                  com.google.protobuf.Duration.Builder,
                  com.google.protobuf.DurationOrBuilder>(
                  getMinDuration(), getParentForChildren(), isClean());
          minDuration_ = null;
        }
        return minDurationBuilder_;
      }
<pre>
Optional. Defines the minimum duration of the guarantee. If specified,
the requested resources will only be provisioned if they can be
allocated for at least the given duration.
</pre>

<code>.google.protobuf.Duration min_duration = 1 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/QueuedResource.java