We want to be able to create URLs like "/foo/bar.html?var=${some_var}" in the FCK editor in Magnolia. We then post-process the content once it comes out of Magnolia to substitute in the variable.

Unfortunately putting a dollar sign in the URL causes "IllegalArgumentException: Illegal group reference" to be thrown in info.magnolia.cms.link.LinkHelper.convertUsingLinkTransformer() as it fails to escape the dollar sign before passing it as the second argument to Matcher.appendReplacement().

The attached patch fixes this issue and adds an extra test case for it.