Using flatlaf-swingx as a dependency in NB Platform module

[Mathieu Bastian <ma...@gephi.org>]

Hi folks, and thanks for the continuous support of Netbeans Platform! I
really enjoy the FlatLaf integration but I'm having issues with one of its
addons.

We still have a lot of SwingX components in our application and I wanted to
add a dependency to flatlaf-swingx
<https://github.com/JFormDesigner/FlatLaf/tree/main/>.

Our NB Platform application is fully Mavenized. When I try to add a
dependency to this library in one of my modules I'm having issues.

This add-on depends on com.formdev:flatlaf
<https://search.maven.org/artifact/com.formdev/flatlaf-swingx/2.1/jar>
which is wrapped in the org-netbeans-libs-flatlaf module.

If I just add the library flatlaf-swingx as dependency. I'm getting
nbm-maven-plugin errors such as

Failed to execute goal
org.apache.netbeans.utilities:nbm-maven-plugin:4.3:manifest
(default-manifest) on project testFlatLaf-module: Uncategorized problems
with NetBeans dependency verification (maybe MNBMODULE-102 or wrong maven
dependency metadata). Supposedly external classes are used in the project's
binaries but the classes are not found on classpath.

On the other hand, if I add flatlaf or the libs-flatlaf to my module's
dependencies I get either this error when the app is run or
ClassNotFoundException.

[org.netbeans.core.CoreBridgeImpl]: Cannot use look and feel class:
com.formdev.flatlaf.FlatDarkLaf
java.lang.ClassNotFoundException: Will not load class
com.formdev.flatlaf.FlatDarkLaf arbitrarily from one of
ModuleCL@1d16d270[org.netbeans.libs.flatlaf]
and ModuleCL@77e9ab07[com.mycompany.testFlatLaf.module] starting from
SystemClassLoader[77 modules]; see http://wiki.netbeans.org/DevFaqModuleCCE

I tried to isolate the problem on a vanilla NB Platform application created
with Netbeans. Still no luck. I've been stuck on this one for a few days so
any pointer is appreciated. I'm also happy to zip my toy project if you
would like to dig into it.

As a more generic description, I'm basically trying to add a library that
depends at runtime on another library that is itself wrapped into a NB
module.

Greetings,

Mathieu