function normalizeToUri(v) {
		if (v && v instanceof URI) {
			return v;
		}
		return new URI(v);
	}
Makes sure that we can safely deal with URI instances.
See return value.

@param {URI|string|undefined} v either a URI instance, a string value or undefined
@returns {URI} a URI instance created from the given argument, or the given argument if it is already a URI instance