Project Reactor TcpServer -> Process incoming chunked message in its entirety - spring-webflux

Question

I have a TcpServer created with Project Reactor, where I want to read in a large String (potentially XML) on the inbound channel, and perform some work on it, and send this back out on the outbound channel.
For me to do the work, I need to have the incoming data in its entirety, without it being chunked. I cannot seem to handle correctly aggregating the data together. Most of the examples in the reactor test code base are just outputting a simple String constant, or a non chunked version of the inbound eg:
https://github.com/reactor/reactor-netty/blob/main/reactor-netty-core/src/test/java/reactor/netty/tcp/TcpServerTests.java#L444
I have tried to String::concat the incoming data like so
inbound.receive().asString().reduce(String::concat)
But the subsequent flatmap never seems to be called.
Perhaps there is something with adding a channelHandler, but I was unable to find something that would aggregate, similar to the JsonObjectDecoder
for example:
TcpServer.create().doOnConnection(conn -> connection.addHandlerLast(new AggregatingStringDecoder))`
import reactor.netty.DisposableServer;
import reactor.netty.tcp.TcpServer;
public class Application {
public static void main(String[] args) {
DisposableServer server =
TcpServer.create()
//inbound.connection.addHandlerLast() Is there a combiner I can use here?
.handle((inbound, outbound) -> {
//Tried to concat here, but then the flatMap is never called.
//return inbound.receive().asString().reduce(String::concat)
return inbound.receive().asString().flatMap(s -> {
//this is chunked, but I need the S to be the complete string.
NettyOutbound out = outbound.sendString(Mono.just(s.toUpperCase()));
return out
})
.bindNow();
server.onDispose()
.block();
}
}