Plugin-registered servlets won't work with uppercase characters in path

A plugin can register servlets through the custom-web.xml file. These servlets are internally mapped to their path, which is done in a case-sensitive fashion.

When a request is being processed, its 'to-lowercase' variant is compared against this mapping. For any servlet that's mapped to a path that contains a uppercase character, this fails.

In order to be backwards compatible as well as resolve this issue, the mapping should use to-lowercase paths.