public String getProtocol() {
        return this.protocol;
    }
<p>
The protocol used for the network traffic between the <code>source</code> and <code>destination</code>. This must
be either <code>TCP</code> or <code>ICMP</code>.
</p>

@return The protocol used for the network traffic between the <code>source</code> and <code>destination</code>.
        This must be either <code>TCP</code> or <code>ICMP</code>.
@see Protocol
aws-java-sdk-networkmonitor/src/main/java/com/amazonaws/services/networkmonitor/model/CreateProbeResult.java