Bug 123625 [cleanup] Generated Serial Version UIDs clean up
Add a fix to the cleanup refactoring which generates missing generated serial version IDs. The code of the existing serial version quickfix has been extracted and is now available in class SerialVersionComputationHelper. For details on how to use this class please refer to the existing quickfix.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/text/correction/SerialVersionHashProposal.java
* @return the computed classpath. May be empty, but not null.
	 * @throws CoreException
	 *             if the project's class path cannot be computed
	 */
	private static String[] computeUserAndBootClasspath(final IJavaProject project) throws CoreException {
		final IRuntimeClasspathEntry[] unresolved= JavaRuntime.computeUnresolvedRuntimeClasspath(project);
		final List resolved= new ArrayList(unresolved.length);
		for (int index= 0; index < unresolved.length; index++) {
			final IRuntimeClasspathEntry entry= unresolved[index];
			final int property= entry.getClasspathProperty();
			if (property == IRuntimeClasspathEntry.USER_CLASSES || property == IRuntimeClasspathEntry.BOOTSTRAP_CLASSES) {
				final IRuntimeClasspathEntry[] entries= JavaRuntime.resolveRuntimeClasspathEntry(entry, project);
				for (int offset= 0; offset < entries.length; offset++) {
					final String location= entries[offset].getLocation();
					if (location != null)
						resolved.add(location);
				}
			}
		}
		return (String[]) resolved.toArray(new String[resolved.size()]);
	}
	/**
	 * Displays an appropriate error message for a specific problem.
	 * 
	 * @param message
	 *            The message to display
	 */
	private static void displayErrorMessage(final String message) {
		final Display display= PlatformUI.getWorkbench().getDisplay();
		if (display != null && !display.isDisposed()) {