private Mapper mapper;
@Override
public Object convert(Object existingDestinationFieldValue, Object sourceFieldValue, Class<?> destinationClass, Class<?> sourceClass) {
MapperAwareSimpleInternal a = (MapperAwareSimpleInternal)sourceFieldValue;
MapperAwareSimpleInternal b = new MapperAwareSimpleInternal();
mapper.map(a, b);
MapperAwareSimpleInternal b2 = new MapperAwareSimpleInternal();
mapper.map(a, b2); //throws NPE in issue45
return b2;
}