Model simplification - single file, no DataNodes?

I'd like to drastically simplify Cayenne projects:

1. Remove DataNode from the XML. DataNode modeling was an idea from the =
days of application servers to bypass JNDI insanity. It allowed a =
developer to quickly connect to a DB. The big problem was that =
DataSources had to be aware of their environment, so I never used the =
built in one for instance. There are custom factories, but if you are to =
use one, you are better off calling it on your own. So I'd rather move =
everything DataNode related to the runtime builder where it belongs:

CayenneRuntime.builder()
   .dataSource(defaultDS)
   .dataSource(specialDS, "map1", "map2")

or even

CayenneRuntime.builder()
   .dataSource(CayenneDataSource.of("jdbc:...."));

2. No multi-file projects ("cayenne-project.xml" should go away, just =
leaving DataMap files). I am still hesitant whether we should support =
more than one DataMap per XML (the only reason is cross-DM =
relationships, but that's a solid reason). For anything else, Cayenne =
has project merging facilities for a long time. So you supply multiple =
projects on startup:

CayenneRuntime.builder()
   .addConfig("p1.xml")
   .addConfig("p2.xml")

3. Remove ObjEntity callbacks support from XML. Just use annotations on =
entities. This is a runtime feature, not a "mapping" feature.

Thoughts?

Andrus=