Cannot add watermark reference to a Map Definition if their schema versions are different

[jng]

If you try to add a 2.3.0 Watermark Definition to a 2.4.0 Map Definition, the watermark is not actually added.

The problem is that there is a separate 2.3.0 and 2.4.0 versions of the WatermarkType auto-generated class and the wrong version of this class is being added (which is being rejected by the Map Definition)

As there is no actual difference between 2.3.0 and 2.4.0, this class should instead be moved into the MaestroAPI library as another common Object Model type.

[jng]

Fixed r6804