This class allows for matching based on a session attribute.
If the specified session attribute exists, its string representation
is retrieved for later sitemap substitution.
Match method to see if the request attribute exists. If it does
have a value the string represenation of attribute is added to
the array list for later sitemap substitution.
Specified by:
match in interface org.apache.cocoon.matching.Matcher
Parameters:
pattern - name of session attribute to find
objectModel - environment passed through via cocoon
Returns:
null or map containing value of session attribute 'pattern'