code: private static ClassDescriptor findInheritanceRoot(ClassDescriptor cld)
      {
          ClassDescriptor result = cld;
          if(cld.getSuperClassDescriptor() != null)
          {
              result = findInheritanceRoot(cld.getSuperClassDescriptor());
          }
          return result;
      }
docs: Returns the root {@link org.apache.ojb.broker.metadata.ClassDescriptor} of the inheriatance
  hierachy of the given descriptor or the descriptor itself if no inheriatance on multiple table is
  used.