Program: 42060
Project: 42060
Buggy source:
public boolean movePlot(IWorld world,String idFrom,String idTo){
  if (!getGenManager(world).movePlot(world,idFrom,idTo)) {
    return false;
  }
  Plot plot1=getPlotById(idFrom,world);
  Plot plot2=getPlotById(idTo,world);
  if (plot1 != null) {
    if (plot2 != null) {
      int idX=getIdX(idTo);
      int idZ=getIdZ(idTo);
      plugin.getSqlManager().deletePlot(idX,idZ,world.getName());
      removePlot(world,idFrom);
      removePlot(world,idTo);
      idX=getIdX(idFrom);
      idZ=getIdZ(idFrom);
      plugin.getSqlManager().deletePlot(idX,idZ,world.getName());
      plot2.setId(idFrom);
      plugin.getSqlManager().addPlot(plot2,idX,idZ,topX(idFrom,world),bottomX(idFrom,world),topZ(idFrom,world),bottomZ(idFrom,world));
      addPlot(world,idFrom,plot2);
      HashMap<String,UUID> allowed=plot2.allowed().getAllPlayers();
      for (      String player : allowed.keySet()) {
        plugin.getSqlManager().addPlotAllowed(player,allowed.get(player),idX,idZ,world.getName());
      }
      HashMap<String,UUID> denied=plot2.denied().getAllPlayers();
      for (      String player : denied.keySet()) {
        plugin.getSqlManager().addPlotDenied(player,denied.get(player),idX,idZ,world.getName());
      }
      idX=getIdX(idTo);
      idZ=getIdZ(idTo);
      plot1.setId(idTo);
      plugin.getSqlManager().addPlot(plot1,idX,idZ,topX(idTo,world),bottomX(idTo,world),topZ(idTo,world),bottomZ(idTo,world));
      addPlot(world,idTo,plot1);
      allowed=plot1.allowed().getAllPlayers();
      for (      String player : allowed.keySet()) {
        plugin.getSqlManager().addPlotAllowed(player,allowed.get(player),idX,idZ,world.getName());
      }
      denied=plot1.denied().getAllPlayers();
      for (      String player : denied.keySet()) {
        plugin.getSqlManager().addPlotDenied(player,denied.get(player),idX,idZ,world.getName());
      }
      setOwnerSign(world,plot1);
      setSellSign(world,plot1);
      setOwnerSign(world,plot2);
      setSellSign(world,plot2);
    }
  }
 else   if (plot2 != null) {
    int idX=getIdX(idTo);
    int idZ=getIdZ(idTo);
    plugin.getSqlManager().deletePlot(idX,idZ,world.getName());
    removePlot(world,idTo);
    idX=getIdX(idFrom);
    idZ=getIdZ(idFrom);
    plot2.setId(idFrom);
    plugin.getSqlManager().addPlot(plot2,idX,idZ,topX(idFrom,world),bottomX(idFrom,world),topZ(idFrom,world),bottomZ(idFrom,world));
    addPlot(world,idFrom,plot2);
    HashMap<String,UUID> allowed=plot2.allowed().getAllPlayers();
    for (    String player : allowed.keySet()) {
      plugin.getSqlManager().addPlotAllowed(player,allowed.get(player),idX,idZ,world.getName());
    }
    HashMap<String,UUID> denied=plot2.denied().getAllPlayers();
    for (    String player : denied.keySet()) {
      plugin.getSqlManager().addPlotDenied(player,denied.get(player),idX,idZ,world.getName());
    }
    setOwnerSign(world,plot2);
    setSellSign(world,plot2);
    removeOwnerSign(world,idTo);
    getGenManager(world).removeSellerDisplay(world,idTo);
  }
  return true;
}

Fixed version (ground truth):
public boolean movePlot(IWorld world,String idFrom,String idTo){
  if (!getGenManager(world).movePlot(world,idFrom,idTo)) {
    return false;
  }
  Plot plot1=getPlotById(idFrom,world);
  Plot plot2=getPlotById(idTo,world);
  if (plot1 != null) {
    if (plot2 != null) {
      int idX=getIdX(idTo);
      int idZ=getIdZ(idTo);
      plugin.getSqlManager().deletePlot(idX,idZ,world.getName());
      removePlot(world,idFrom);
      removePlot(world,idTo);
      idX=getIdX(idFrom);
      idZ=getIdZ(idFrom);
      plugin.getSqlManager().deletePlot(idX,idZ,world.getName());
      plot2.setId(idFrom);
      plugin.getSqlManager().addPlot(plot2,idX,idZ,topX(idFrom,world),bottomX(idFrom,world),topZ(idFrom,world),bottomZ(idFrom,world));
      addPlot(world,idFrom,plot2);
      HashMap<String,UUID> allowed=plot2.allowed().getAllPlayers();
      for (      String player : allowed.keySet()) {
        plugin.getSqlManager().addPlotAllowed(player,allowed.get(player),idX,idZ,world.getName());
      }
      HashMap<String,UUID> denied=plot2.denied().getAllPlayers();
      for (      String player : denied.keySet()) {
        plugin.getSqlManager().addPlotDenied(player,denied.get(player),idX,idZ,world.getName());
      }
      idX=getIdX(idTo);
      idZ=getIdZ(idTo);
      plot1.setId(idTo);
      plugin.getSqlManager().addPlot(plot1,idX,idZ,topX(idTo,world),bottomX(idTo,world),topZ(idTo,world),bottomZ(idTo,world));
      addPlot(world,idTo,plot1);
      allowed=plot1.allowed().getAllPlayers();
      for (      String player : allowed.keySet()) {
        plugin.getSqlManager().addPlotAllowed(player,allowed.get(player),idX,idZ,world.getName());
      }
      denied=plot1.denied().getAllPlayers();
      for (      String player : denied.keySet()) {
        plugin.getSqlManager().addPlotDenied(player,denied.get(player),idX,idZ,world.getName());
      }
      setOwnerSign(world,plot1);
      removeSellSign(world,plot1.getId());
      removeAuctionSign(world,plot1.getId());
      setOwnerSign(world,plot2);
      removeSellSign(world,plot2.getId());
      removeAuctionSign(world,plot2.getId());
    }
  }
 else   if (plot2 != null) {
    int idX=getIdX(idTo);
    int idZ=getIdZ(idTo);
    plugin.getSqlManager().deletePlot(idX,idZ,world.getName());
    removePlot(world,idTo);
    idX=getIdX(idFrom);
    idZ=getIdZ(idFrom);
    plot2.setId(idFrom);
    plugin.getSqlManager().addPlot(plot2,idX,idZ,topX(idFrom,world),bottomX(idFrom,world),topZ(idFrom,world),bottomZ(idFrom,world));
    addPlot(world,idFrom,plot2);
    HashMap<String,UUID> allowed=plot2.allowed().getAllPlayers();
    for (    String player : allowed.keySet()) {
      plugin.getSqlManager().addPlotAllowed(player,allowed.get(player),idX,idZ,world.getName());
    }
    HashMap<String,UUID> denied=plot2.denied().getAllPlayers();
    for (    String player : denied.keySet()) {
      plugin.getSqlManager().addPlotDenied(player,denied.get(player),idX,idZ,world.getName());
    }
    setOwnerSign(world,plot2);
    setSellSign(world,plot2);
    removeOwnerSign(world,idTo);
    removeSellSign(world,idTo);
    removeAuctionSign(world,idTo);
  }
  return true;
}