Bug 37197 Basepath for relative pathes in JAR-exporter
The basepath for the JAR-exporter is the eclipse-install-directory. I prefer it to be the root of the project (the description is saved in), so that relative pathes end inside the project. Now: <jardesc> <jar path="workspace/projectdir/jar.jar"/> Desired: <jardesc> <jar path="jar.jar"/> Reason: To make the jardesc-files portable for shared projects
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/jarpackager/JarPackageData.java
* Finds the class files for the given java file 
	 * and returns them.
	 * <p>
	 * This is a hook for subclasses which want to implement
	 * a different strategy for finding the class files. The default
	 * strategy is to query the class files for the source file
	 * name attribute. If this attribute is missing then all class
	 * files in the corresponding output folder are exported.
	 * </p>
	 * <p>
	 * A CoreException can be thrown if an error occurs during this
	 * operation. The <code>CoreException</code> will not stop the export
	 * process but adds the status object to the status of the
	 * export runnable.
	 * </p>
	 * 
	 * @param	javaFile a .java file
	 * @return	an array with class files or <code>null</code> to used the default strategy
	 * @throws	CoreException	if find failed, e.g. I/O error or resource out of synch
	 * @see	IJarExportRunnable#getStatus()
	 */
	public IFile[] findClassfilesFor(IFile javaFile) throws CoreException {
		return null;
	}
	/**
	 * Creates and returns a JarWriter for this JAR package.
	 *
	 * @param parent	the shell used to display question dialogs,
	 *				 	or <code>null</code> if "false/no/cancel" is the answer
	 * 					and no dialog should be shown