public static ClientDecoration ofRpc(DecoratingRpcClientFunction decorator) {
        return builder().addRpc(decorator).build();
    }
Creates a new instance from a single {@link DecoratingRpcClientFunction}.

@param decorator the {@link DecoratingRpcClientFunction} that transforms an {@link RpcClient} to another
core/src/main/java/com/linecorp/armeria/client/ClientDecoration.java