private com.google.protobuf.SingleFieldBuilderV3<
            com.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfig,
            com.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfig.Builder,
            com.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfigOrBuilder>
        getPrivateClusterConfigFieldBuilder() {
      if (privateClusterConfigBuilder_ == null) {
        privateClusterConfigBuilder_ =
            new com.google.protobuf.SingleFieldBuilderV3<
                com.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfig,
                com.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfig.Builder,
                com.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfigOrBuilder>(
                getPrivateClusterConfig(), getParentForChildren(), isClean());
        privateClusterConfig_ = null;
      }
      return privateClusterConfigBuilder_;
    }
<pre>
Optional. Configuration for private workstation cluster.
</pre>

<code>
.google.cloud.workstations.v1.WorkstationCluster.PrivateClusterConfig private_cluster_config = 12 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-workstations/proto-google-cloud-workstations-v1/src/main/java/com/google/cloud/workstations/v1/WorkstationCluster.java