Improved error message in GenericEntity.java - no functional change. The improved message should help developers solve the problem causing the exception.

This has been discussed before, but I will mention it again for instruction: GenericEntity instances that are kept in the entity cache are shared among multiple threads. Therefore, they must be immutable. If you get a GenericEntity instance from the cache and you want to modify it, you must clone it first.


git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1547790 13f79535-47bb-0310-9956-ffa450edef68