DERBY-6600: Make it possible to bind functions to methods in the org.apache.derby.optional.api package; tests passed cleanly on derby-6600-02-aa-addAPIpackage.diff.

git-svn-id: https://svn.apache.org/repos/asf/db/derby/code/trunk@1600928 13f79535-47bb-0310-9956-ffa450edef68