@java.lang.Override
      public int getProtocolValue() {
        return protocol_;
      }
<pre>
Specifies the network protocol of the agent. When not specified, the
default value of NetworkProtocol NETWORK_PROTOCOL_HTTPS is used.
</pre>

<code>.google.storagetransfer.v1.S3CompatibleMetadata.NetworkProtocol protocol = 3;</code>

@return The enum numeric value on the wire for protocol.
java-storage-transfer/proto-google-cloud-storage-transfer-v1/src/main/java/com/google/storagetransfer/v1/proto/TransferTypes.java