Refactor MappingContext.java

[Degubi]

• Refactor ParseClassModelFunction into a static factory that creates Function<Class<?>, ClassModel> (named as createParseClassModelFunction). Removes an inner interface.
• Remove classModelIterator, not used anywhere. Removes an inner class.
• Use the return value of 'classes.computeIfAbsent' instead of calling 'computeIfAbsent' and then 'get' after it, saves using 'get'.
• Add '<?>'-s, avoids some warnings.
• No changes in behavior, just to remove some bloat.

Signed-off-by: Gyúróczki Gergő gergonoorbi@gmail.com

[aguibert]

LGTM