Cannot configure JREs correctly

[LorenzoBettini]

I've just started experimenting with Eclipse installed as a flatpak (I have quite experience with Eclipse, but I had never tried the flatpak version).

I cannot seem to be able to set JREs properly.

The JRE that comes with JustJ does not allow me to run a Maven build (I guess because it's not a JDK but only a JRE? I never used JustJ anyway in the past). When I try to set the available JDKs I installed (Fedora 36):

ll /usr/lib/jvm
total 76
lrwxrwxrwx. 1 root root  26 May 18 14:27 java -> /etc/alternatives/java_sdk
lrwxrwxrwx. 1 root root  29 May 18 14:27 java-11 -> /etc/alternatives/java_sdk_11
lrwxrwxrwx. 1 root root  37 May 18 14:27 java-11-openjdk -> /etc/alternatives/java_sdk_11_openjdk
drwxr-xr-x. 1 root root  70 May 18 14:27 java-11-openjdk-11.0.15.0.10-1.fc36.x86_64
lrwxrwxrwx. 1 root root  29 May 18 14:27 java-17 -> /etc/alternatives/java_sdk_17
lrwxrwxrwx. 1 root root  37 May 18 14:27 java-17-openjdk -> /etc/alternatives/java_sdk_17_openjdk
drwxr-xr-x. 1 root root  70 May 18 14:27 java-17-openjdk-17.0.3.0.7-1.fc36.x86_64
...

Eclipse changes the path as follows:

and then I cannot still run Maven from Eclipse because it cannot find

Error: Could not find or load main class org.codehaus.plexus.classworlds.launcher.Launcher
Caused by: java.lang.ClassNotFoundException: org.codehaus.plexus.classworlds.launcher.Launcher

[Mailaender]

Possible duplicate of #47

[LorenzoBettini]

Maybe: that bug is quite old, and the error message I get is slightly different: it complains that JAVA_HOME is not set