public Builder addNetworkConfigs(int index, com.google.cloud.tpu.v2.NetworkConfig value) {
      if (networkConfigsBuilder_ == null) {
        if (value == null) {
          throw new NullPointerException();
        }
        ensureNetworkConfigsIsMutable();
        networkConfigs_.add(index, value);
        onChanged();
      } else {
        networkConfigsBuilder_.addMessage(index, value);
      }
      return this;
    }
<pre>
Optional. Repeated network configurations for the TPU node. This field is
used to specify multiple networks configs 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>
repeated .google.cloud.tpu.v2.NetworkConfig network_configs = 49 [(.google.api.field_behavior) = OPTIONAL];
</code>
java-tpu/proto-google-cloud-tpu-v2/src/main/java/com/google/cloud/tpu/v2/Node.java