code: public HashSet<String> getClassnames(String pkgname) {
      if (m_NameCache.containsKey(pkgname))
        return m_NameCache.get(pkgname);
      else
        return new HashSet<>();
    }
docs: Returns all the classes for the given package.
  
  @param pkgname	the package to get the classes for
  @return		the classes (sorted by name)