iPojo nature is broken in latest Eclipse versions at least from 2024-12

[gevegab]

The problem comes from the way the IJavaProject is obtained for a given project :

(IJavaProject) project.getNature(JavaCore.NATURE_ID)

This worked in previous versions because JavaProject directly implemented IJavaNature.

This is no longer the case since this PR eclipse-jdt/eclipse.jdt.core#1916 was merged.

The official API for getting the IJavaProject given an IProject is :

https://help.eclipse.org/latest/topic/org.eclipse.jdt.doc.isv/reference/api/org/eclipse/jdt/core/JavaCore.html#create(org.eclipse.core.resources.IProject)