code: public final void setCustomResponseHeader (@Nonnull @Nonempty final String sName,
                                               @Nonnull @Nonempty final String sValue)
    {
      ValueEnforcer.notEmpty (sName, "Name");
      ValueEnforcer.notEmpty (sValue, "Value");
  
      m_aResponseHeaderMap.setHeader (sName, sValue);
    }
docs: Sets a response header to the response according to the passed name and
  value. An existing header entry with the same name is overridden.<br>
  <b>ATTENTION:</b> You should only use the APIs that {@link UnifiedResponse}
  directly offers. Use this method only in emergency and make sure you
  validate the header field and allowed value!
  
  @param sName
  Name of the header. May neither be <code>null</code> nor empty.
  @param sValue
  Value of the header. May neither be <code>null</code> nor empty.