def add_owners_for(klass, hash, &factory)
      owner = missing_owner_for(klass, hash) || return
      logger.debug { "The migrator is adding #{klass.qp} owner #{owner}..." }
      @owners << owner
      hash[owner] = yield
      add_owners_for(owner, hash, &factory)
    end
def add_owners_for(klass, hash, &factory)
      owner = missing_owner_for(klass, hash) || return
      logger.debug { "The migrator is adding #{klass.qp} owner #{owner}..." }
      @owners << owner
      hash[owner] = yield
      add_owners_for(owner, hash, &factory)
    end
Adds missing owner classes to the migration class path hash (with empty paths)
 for the given migration class.

 @param [Class] klass the migration class
 @param [{Class => Object}] hash the class map
 @yield the map entry for a new owner