See http://www.avaje.org/topic-132.html

Oracle DB treats empty strings as null. This meant there was a bug in Ebean for certain circumstances...
- optimistic concurrency checking on Update / Delete
- no version column
- likely performing insert then update or update update on the same bean... and one of the properties was set to an empty string.

This results in an Optimistic concurrency error as the empty strings needed to be treated as null.