New test cases are needed for illegal arguments of newInstance.
One strategy is to define classes in a new package along with metadata, but no mapping (since these are error classes). A new test should try to instantiate the classes using the newInstance method and verify that JDOUserException is thrown.
Classes to test include:
Abstract class with abstract method not declared as a property (missing metadata for the method)
Interface with method not declared as a property (missing metadata for the method)
Concrete class with missing public no-args constructor