The Kerr-Schild ansatz for the Nariai spacetime and the generating   conjecture
  We will show that the Nariai metric, i.e. the static spherically symmetric vacuum spacetime with a cosmological constant, admits a conformally Kerr-Schild spacetime representation. We find the vacuum solutions of the Einstein-Maxwell equations for the Nariai metric using the Horsky-Mitskievich generating conjecture. 
Milan Stefanik, Jan Horsky