That's my feeling, too. But perhaps it is even better to split BeanMapping and MappingMethod all together:
* let there be one MappingMethod instance for every method to be generated (not more, not less)
* let MappingMethod reference the related BeanMapping (which could be a n-1 relation)
* reverse-mappings would yield new instances of BeanMapping and MappingMethod - I don't think that link between a method and its reverse-method is required later on anyway, is it?