*
* @param string $entity entity name in various formats e.g. Contribution, contribution, OptionValue, option_value, UFJoin, uf_join
* @return string $entity entity name in underscore separated format
*
* @param string $entity entity name in various formats e.g. Contribution, contribution, OptionValue, option_value, UFJoin, uf_join
* @return string $entity entity name in underscore separated format