private void ensureNetworkConfigsIsMutable() {
      if (!((bitField0_ & 0x00000080) != 0)) {
        networkConfigs_ =
            new java.util.ArrayList<com.google.cloud.tpu.v2.NetworkConfig>(networkConfigs_);
        bitField0_ |= 0x00000080;
      }
    }
<pre>
Network configurations for the TPU node. network_config and network_configs
are mutually exclusive, you can only specify one of them. If both are
specified, an error will be returned.
</pre>

<code>.google.cloud.tpu.v2.NetworkConfig network_config = 36;</code>
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/Node.java