private String titleFor(Class<? extends CommandMarker> plugin) {
		if (!titles.containsKey(plugin)) {
			throw new IllegalArgumentException("Missing title for " + plugin);
		}
		return titles.get(plugin);
	}
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