ClassModel. Such an
element can appear when traversing a ClassModel unless otherwise
specified, be supplied to a ClassBuilder, and be processed by a
ClassTransform.
AccessFlags, and ClassFileVersion are member elements of a
class that appear exactly once during the traversal of a ClassModel.
Superclass and Interfaces may be absent or appear at most
once. A ClassBuilder may provide an alternative superclass if it is
not defined but required.
Membership Elements, MethodElement, FieldElement, CodeElement