Xerces used to be released as a single jar (xerces.jar), but was split into two jars, one containing the API (xml-apis.jar) and one containing the implementations of those APIs (xercesImpl.jar). Many older Maven POMs still declare a dependency on xerces.jar. At some point in the past, Xerces was also released as xmlParserAPIs.jar, which some older POMs also depend on.
URL patterns use an extremely simple syntax. Every character in a pattern must match the corresponding character in the URL path exactly, with two exceptions. At the end of a pattern, /* matches any sequence of characters from that point forward. The pattern *.extension matches any file name ending with extension. No other wildcards are supported, and an asterisk at any other position in the pattern is not a wildcard.
First, the container prefers an exact path match over a wildcard path match. Second, the container prefers to match the longest pattern. Third, the container prefers path matches over filetype matches. Finally, the pattern <url-pattern>/</url-pattern> always matches any request that no other pattern matches