public THttpServiceBuilder decorate(Function<? super RpcService, ? extends RpcService> decoratorFunction) {
        requireNonNull(decoratorFunction, "decoratorFunction");
        if (this.decoratorFunction == null) {
            this.decoratorFunction = decoratorFunction;
        } else {
            this.decoratorFunction = this.decoratorFunction.andThen(decoratorFunction);
        }
        return this;
    }
A {@code Function<? super RpcService, ? extends RpcService>} to decorate the {@link RpcService}.
thrift/thrift0.13/src/main/java/com/linecorp/armeria/server/thrift/THttpServiceBuilder.java