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/internal/ui/jarpackager/JarFileExportOperation.java
else {
			outputContainer= createFolderHandle(outputPath);
			if (outputContainer == null || !outputContainer.isAccessible()) {
				String msg= JarPackagerMessages.getString("JarFileExportOperation.outputContainerNotAccessible"); 
				throw new CoreException(new Status(IStatus.ERROR, JavaPlugin.getPluginId(), IJavaStatusConstants.INTERNAL_ERROR, msg, null));
			}
		}
		
		boolean hasErrors= hasCompileErrors(file);
		boolean hasWarnings= hasCompileWarnings(file);
		boolean canBeExported= canBeExported(hasErrors, hasWarnings);
		if (!canBeExported)
			return Collections.EMPTY_LIST.iterator();
		reportPossibleCompileProblems(file, hasErrors, hasWarnings, canBeExported);
		IContainer classContainer= outputContainer;
		if (pathInJar.segmentCount() > 1)
			classContainer= outputContainer.getFolder(pathInJar.removeLastSegments(1));
			
		if (fExportedClassContainers.contains(classContainer))
			return Collections.EMPTY_LIST.iterator();
			
		if (fClassFilesMapContainer == null || !fClassFilesMapContainer.equals(classContainer)) {
			fJavaNameToClassFilesMap= buildJavaToClassMap(classContainer);
			if (fJavaNameToClassFilesMap == null) {
				
				IPath location= classContainer.getLocation();
				String containerName= "";  
				if (location != null)
					containerName= location.toFile().toString();
				String msg= JarPackagerMessages.getFormattedString("JarFileExportOperation.missingSourceFileAttributeExportedAll", containerName);