code: public RelationshipPrefetcher createRelationshipPrefetcher(ClassDescriptor anOwnerCld, String aRelationshipName)
      {
          ObjectReferenceDescriptor ord;
          
          ord = anOwnerCld.getCollectionDescriptorByName(aRelationshipName);
          if (ord == null)
          {
              ord = anOwnerCld.getObjectReferenceDescriptorByName(aRelationshipName);
              if (ord == null)
              {
                  throw new PersistenceBrokerException("Relationship named '" + aRelationshipName
                          + "' not found in owner class " + (anOwnerCld != null ? anOwnerCld.getClassNameOfObject() : null));
              }
          }
          return createRelationshipPrefetcher(ord);
      }
docs: create either a CollectionPrefetcher or a ReferencePrefetcher