@Override
			public int compare(Class<? extends CommandMarker> arg0, Class<? extends CommandMarker> arg1) {
				List<Class<? extends CommandMarker>> sorted = new ArrayList<Class<? extends CommandMarker>>(
						titles.keySet());
				int diff = sorted.indexOf(arg0) - sorted.indexOf(arg1);
				return diff != 0 ? diff : arg0.getSimpleName().compareTo(arg1.getSimpleName());
			}
A mapping from class to Title in the doc. Insertion order will become rendering order.
documentation-toolchain/src/test/java/org/springframework/xd/documentation/ShellReferenceDoc.java