code: public void setDataType(Series.DataType dataType) {
  
      if (dataType != null && this.dataType != null && this.dataType != dataType) {
        throw new IllegalArgumentException(
            "Different Axes (e.g. Date, Number, String) cannot be mixed on the same chart!!");
      }
      this.dataType = dataType;
    }
docs: Getters /////////////////////////////////////////////////