A couple of questions

[PavelTurk]

> Starting in model world (Configuration/ResolvedModule) is right and you first need to find the Configuration containing the moduleX that moduleY reads, this should do it:
>
Yes, I understand it, I sent a piece of real application code, so it was a little different.
> Once you have the Configuration then you need to find the ModuleLayer that was reifed from that Configuration, this should do it:
>
>         ModuleLayer layer = layerC.parents().stream()
>                 .filter(l -> l.configuration() == cf)
>                 .findAny()
>                 .orElseThrow();
>
> Can you try it?
>
Yes, it worked. Thank you very much for your help. I didn't understand that we could map layer and modules of this layer by configuration.
So I just created Map where as a key I used the configuration of all layers and after that
for (var readModule : m.reads()) {
     var layer = moduleLayersByConfiguration.get(readModule.configuration());
}

Several notes:

1. Your code `ModuleLayer layer = layerC.parents().stream()...` didn't find layer if moduleX was in boot layer, but not in direct parents of layerC. In our example 4
layers:
1) boot
2) layerA (parent - boot) has moduleX
3) layerB (parent - boot) has moduleX
4) layerC (parents - layerA, layerB) has moduleY

2. Please see this diagram https://i.stack.imgur.com/ss2os.png that was generated for real application using reads and ResolvedModules (the topic of this thread).
Here we have two layers - the right is a boot layer and the left is a webserver layer. The program must show reads of com.google.gson. Reads are shown using dashed arrows.
a) we see that gson reads 5 modules. At the same time gson requires only 1 module:
module com.google.gson {
     exports com.google.gson;
     exports com.google.gson.annotations;
     exports com.google.gson.reflect;
     exports com.google.gson.stream;

     requires transitive java.sql;
}

Do I understand it correctly that extra 4 modules are read via java.sql?

3. Do I understand it correctly if some explicit module (with module-info) from webserver layer will require any automatic module from webserver layer then this explicit
module will read ALL automatic modules from both layers?

Best regards, Pavel