public String getProtocol() {
        return this.protocol;
    }
<p>
The protocol for the health check request. If you specify <code>grpc</code>, then your service must conform to
the <a href="https://github.com/grpc/grpc/blob/master/doc/health-checking.md">GRPC Health Checking Protocol</a>.
</p>

@return The protocol for the health check request. If you specify <code>grpc</code>, then your service must
        conform to the <a href="https://github.com/grpc/grpc/blob/master/doc/health-checking.md">GRPC Health
        Checking Protocol</a>.
@see VirtualGatewayPortProtocol
aws-java-sdk-appmesh/src/main/java/com/amazonaws/services/appmesh/model/VirtualGatewayHealthCheckPolicy.java