The regex used in ChatClickData doesn't match on valid URLs which use an IP4 address, port, hash (#), or have comma in the query string. This makes a large variety of valid URLs "un-clickable" in the Chat GUI.

Pattern pattern = Pattern.compile("^(?:(https?)://)?([-\\w_\\.]{2,}\\.[a-z]{2,4})(/\\S*)?$");

As a fix, the proposed regex will accept either TLD or IP4, optionally allows port, and accepts a hash or commas in the query string:

Pattern pattern = Pattern.compile("^(https?:\\/\\/)?"+ // protocol
      "((([a-z\\d]([a-z\\d-]*[a-z\\d])*)\\.)+[a-z]{2,}|"+ // domain name
      "((\\d{1,3}\\.){3}\\d{1,3}))"+ // OR ip (v4) address
      "(\\:\\d+)?(\\/[-a-z\\d%_.~+]*)*"+ // port and path
      "(\\?[;&a-z\\d%_.~+=-]*)?"+ // query string
      "(\\#[-a-z\\d_]*)?$"); // hash

Here's a JSFiddle showing the current and proposed regexes in action:

http://jsfiddle.net/mwoodman/UycV9/

Note that the current regex is failing to match on more than half of the URLs tested (2766 out of 4704). The proposed regex passes all of the URLs tested.