Currently when you invoke the entity classes from DB or the standard entity 
class wizard without having created a persistence unit the generated classed 
are not compilable due to missing javax.persistence.* classes. It would be nice 
if there was a possibility to add a library containing the required classes in 
the wizards. Therefore, based on Andrei's idea I'd like to suggest removing the 
'create pu' button from the step two (step one in the standard ec wizard) in 
the wizards and putting it to an additional step, which would also contain 
options for adding a persistence provider library to the probject. 

The additional panel would contain three radio buttons; one for creating a pu, 
one for adding a library to the project and one for taking no action. The 
create pu option would have a button for customizing it (it would basically 
open the dialog that's now have for creating a pu) and the add library button 
would have an associated combo box for selecting the provider library. The 
space freed by the moving of the create pu button in the second panel could be 
used by future enchancements in the wizards.

If needed, I can illustrate the proposal with some ASCII art.