public void setProtocol(final String protocol) {
        this.protocol = protocol;
    }
Sets protocol.
@param protocol the protocol
shenyu-plugin/shenyu-plugin-proxy/shenyu-plugin-rpc/shenyu-plugin-dubbo/shenyu-plugin-dubbo-common/src/main/java/org/apache/shenyu/plugin/dubbo/common/cache/DubboParam.java