Javadoc needs to explain where the results from the Transferrable interface implementation in DataHandler are derived.

getTransferDataFlavors: Javadoc needs to explain how this is implemented.
1. It's derived from DataContentHandler.getTransferDataFlavors
2. if no user defined dch is provided, then private implementations DataSourceDataContentHandler
and ObjectDataContentHandler are used, and their behavior is ???

There's no way I can determine from the doc what the result should be for testing.

isDataFlavorSupported: Javadoc needs to indicate that it's implemented in terms of
getTransferDataFlavors. Then I can verify against that result.

Note that if there's a distinction between the requirements of these for any Jaf implentation, and the reference implementation, then both need to be documented, so that appropriate functional, and jck tests can be written.