Just a letter to my future self:

When you use Properties and creates the entries, remember to avoid the whitespaces. The properties are inserted as-they-are, so no trimming occurs.

It might sound trivial, but it wasted at least an hour of my time, while I was searching for a bug in a totally wrong department…

Pure evil:

Properties p = new Properties;
p.put("java.naming.factory.initial",
         " org.apache.openejb.client.LocalInitialContextFactory");