Dozer is a popular bean-to-bean mapping library. This functionality is typically needed when switching between domain models, e.g. to isolate the internal representation of a domain model from the model published to clients through a REST API.
Dozer has a pluggable class loading configuration which allows to set a custom class loader for classes and resources. However Dozer was not designed with OSGi in mind. Custom class loaders are set on a Dozer singleton. This combined with the lazy loading of mapping definition files can generate unexpected results.