See the documentation for the generic ColumnBuilder T  class. This class cannot be used directly.

This class is used to dynamically create a column. This class cannot be instantiated directly. It is given as an argument to the calculation method for classes inheriting from the Spotfire.Dxp.Application.Extension.CustomColumnMethod<T> class. Classes inheriting from the Spotfire.Dxp.Application.Extension.CustomCalculation<TSettings, TResults> class can also retrieve instances of this class by using the Spotfire.Dxp.Application.Extension.CustomCalculation<TSettings, TResults>.GetColumnBuilder<TDataValue> method.