Some URLs are filtered out by the crawl url filter for special characters (by default). One of these is the jsessionid urls such as:
http://www.somesite.com;jsessionid=A8D7D812B5EFD3099F099A760F779E3B?query=string
We want to get rid of the jessionid and keep everything else so that it looks like this:
http://www.somesite.com?query=string
Below is a regular expression for the regex-normalize.xml file used by the RegexUrlNormalizer that sucessfully removes jsessionid strings while leaving the hostname and querystring. I have also attached a patch for the regex-normalize.xml.template file that adds the following expression.
<regex>
<pattern>(.)(;jsessionid=[a-zA-Z0-9]{32})(.)</pattern>
<substitution>$1$3</substitution>
</regex>