this is a critical case: because of the previous extension of Module11 which is in a different hierarchy, DataType21 is looked for in Module11 and its parents; finally it is not found and the definition is ignored for order calculation
if there is no other class or module after the last datatype, it won’t show up in _constantOrder however, the order of eClassifiers can still be reconstructed note that this can not be tested if the test is executed as part of the whole testsuite since there will be classes and modules created within other test files