I was looking back at this, and this new o.a.a.server.zookeeper.ZooReaderWriterFactory does not appear to be used at all. Is that intended? Is this a bug? Should this class be deleted?
Also, the problem originally reported (singleton with public constructor) seems to have shifted to this ZooReaderWriterFactory class instead of the original ZooReaderWriter.
Since this has already shipped in 1.6.1, I suppose a new issue should be opened to deal with it, but before I do that, I'm kind of curious what the intentions were for this unused class.