Returns the custom DataFlavor associated
with the encapsulated object or null if the FileDrop.TransferableObject.Fetcher
constructor was used without passing a Class.
Returns a two- or three-element array containing first
the custom data flavor, if one was created in the constructors,
second the default DATA_FLAVOR associated with
TransferableObject, and third the
java.awt.datatransfer.DataFlavor.stringFlavor.