+ // The number of contributors set in the AliESDVertex object is the
+ // number of tracklets used to determine the vertex position
+ // If this number is <1, the procedure could not find a vertex position
+ // and by default the Z coordinate is set to 0
+ // Number of contributors = -1 --> No tracklets
+ // Number of contributors = -2 --> No SPD recpoints
+ virtual AliESDVertex* FindVertexForCurrentEvent(TTree *itsClusterTree);