docs: private static int _parseEndOfLine (@Nonnull final String sHeaderPart, final int nEnd)
    {
      int nIndex = nEnd;
      for (;;)
      {
        final int nOffset = sHeaderPart.indexOf ('\r', nIndex);
        if (nOffset == -1 || nOffset + 1 >= sHeaderPart.length ())
          throw new IllegalStateException ("Expected headers to be terminated by an empty line.");
  
        if (sHeaderPart.charAt (nOffset + 1) == '\n')
          return nOffset;
        nIndex = nOffset + 1;
      }
    }