How can I enable "Host" and "Fragments (user interface)" to call each other?

[davidleetw]

Assuming:
Host plugin H has 3 Fragments(UI) fa、fb and fc

Requirements:

1. H has to invoke fa、fb to show their UIs.
2. fb has to invoke fa、fc to show their UIs.

For classpath, I use Build Path -> add bin Class Folder

Java 11 + Eclipse 2021-06 + RAP 3.17
Maven 3.8 + Tycho 2.75, no issue in compiling/building the war file

Java 21 + Eclipse 2024-06 + RAP 3.29
Maven 3.9.12 + Tycho 5.01, error messages:
[ERROR] Failed to execute goal org.eclipse.tycho:tycho-compiler-plugin:5.0.1:compile (default-compile) on project...: Compilation failure:

What's the right way for the requirements stated as above?

Thank you for help!

[davidleetw]

I solved that with Extension Point.
Thank you!