public static ClientDecoration ofRpc(Function<? super RpcClient, ? extends RpcClient> decorator) {
        return builder().addRpc(decorator).build();
    }
Creates a new instance from a single decorator {@link Function}.

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