Currently, Plastic assets, early, that all instance fields are private. Instead, it should check fields as transformations are applied to them, and ensure that they are merely non-public. Access to the fields from other classes (including inner classes) must be routed through access methods.
Inner classes will now need a limited set of transformations, to handle the cases where a protected or package private field is directly accessed, in which case, the appropriate accessor method will be used instead.
It seems possible that two transformed classes that each access the other's non-public fields might cause an endless loop; if so, this should be identified and reported.