Not able to load resources from classpath - gluon

Question

I build this app and tried to move to mobile/native desktop. In mobile and native I have error loading resources from classpath. Error in desktop version:
Caused by: java.lang.NullPointerException
at org.fxapps.alphabet.AlphabetFX.bulkDetailsImages(AlphabetFX.java:178)
It refers to this line: https://github.com/jesuino/alphabetfx/blob/master/alphabetfx/src/main/java/org/fxapps/alphabet/AlphabetFX.java#L178
However, notice I can't also load a single file, it returns null.
Check my projects: https://github.com/jesuino/alphabetfx
I noticed the same error with android app using adb.
Different approaches were tried:
Used latest version for gluon
Put everything in the same project
Notice also that it works locally, with Java only. I can't even load the file on root classpath (/details).
I have the same kind of apply of app that works greatly: https://github.com/jesuino/battleship-game
Could this be caused because I have too much assets in my classpath? Or is there some sort of cache? I can see in debug logs that it handles most of my assets.
You can reproduce the error by:
Build the project using mvn clean install
Then go into alphabetfx-app and run mvn client:build client:package
Try to run the executable: ./target/client/x86_64-linux/AlphabetFXApp
Please help!
EDIT:
As pointed by Jose in Twitter[1], listing resources from the JAR or native bits (without a FS) won't work, hence I am using a file called "details.txt". However I still get a null when trying to read it. I will continue with this approach and update this with my solution when I find it.
[1] https://twitter.com/JPeredaDnr/status/1323348851345002502

Answer 1

I found the solution!
It was graalvm not copying my file to the native image. See this:
https://github.com/oracle/graal/blob/master/substratevm/Resources.md
The default configuration does not include all files in classpath into the native image. What I had to do was to rename my file to have a supported extension, I used ".dat" since ".txt" is not supported. See the list of supported resource extension by default:
File: ${App}/target/client/x86_64-linux/gvm/resourceconfig-x86_64-linux.json
{
"resources": [
{"pattern": ".*\\.png$"},
{"pattern": ".*\\.jpg$"},
{"pattern": ".*\\.jpeg$"},
{"pattern": ".*\\.gif$"},
{"pattern": ".*\\.bmp$"},
{"pattern": ".*\\.ttf$"},
{"pattern": ".*\\.raw$"},
{"pattern": ".*\\.xml$"},
{"pattern": ".*\\.fxml$"},
{"pattern": ".*\\.css$"},
{"pattern": ".*\\.gls$"},
{"pattern": ".*\\.json$"},
{"pattern": ".*\\.dat$"},
{"pattern": ".*\\.license$"},
{"pattern": ".*\\.frag$"},
{"pattern": ".*\\.vert$"},
{"pattern": ".*\\.obj$"}
]
}