If not null, a plain object with properties:
     type                                    [type: String]                          - type of cell
     rowOrdinals                             [type: Array]                           - the row tuple ordinals
     columnOrdinals                          [type: Array]                           - the column tuple ordinals
     nodes                                   [type: Array]                           - selected nodes    
     relationshipMetricSetBindingId          [type: String]                          - relationshipMetricSetBindingId
     infoMetricSetBindingId                  [type: String]                          - infoMetricSetBindingId