code: public static boolean hasKnownProtocol (@Nullable final String sURI)
    {
      if (StringHelper.hasNoText (sURI))
        return false;
      return URLProtocolRegistry.getInstance ().hasKnownProtocol (sURI) || sURI.startsWith ("//");
    }
docs: Special "has known protocol" version that also supports the pseudo protocol
  "//" that maps to either "http" or "https" depending on the surrounding
  setup.
  
  @param sURI
  Source URI. MAy be <code>null</code>.
  @return <code>true</code> if the URI has a known protocol or "//".