Bug 123946 [quick assist] "Add keyword 'final' to all unchanged variables and properties"
This function can be provide with the "Format" function
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/fix/CleanUpRefactoringWizard.java
private final ICleanUp[] fPreviewCleanUps;
			private boolean fUpdateBlocked;
			public CleanUpPreview(Composite parent, Map map, ICleanUp[] cleanUps) {
				super(map, parent);
				fPreviewCleanUps= cleanUps;
				fUpdateBlocked= false;
			}
			/**
			 * {@inheritDoc}
			 */
			protected void doFormatPreview() {
			
				StringBuffer buf= new StringBuffer();
				for (int i= 0; i < fPreviewCleanUps.length; i++) {
					buf.append(fPreviewCleanUps[i].getPreview());
					buf.append("\n"); 
				}
				format(buf.toString());
			}
			
			private void format(String text) {
		        if (text == null) {
		            fPreviewDocument.set(""); 
		            return;
		        }