code: public void setLongHeader (@Nonnull @Nonempty final String sName, final long nValue)
    {
      _setHeader (sName, Long.toString (nValue));
    }
docs: Set the passed header as a number.
  
  @param sName
  Header name. May neither be <code>null</code> nor empty.
  @param nValue
  The value to be set. May not be <code>null</code>.