get _minTimestamp() {
      return this._minDate.valueOf() / 1000;
    }
@class

Abstract base class for Calendar, DayPicker, MonthPicker and YearPicker that adds support for:
 - common properties (timestamp, selectedDates): declarations and methods that operate on them
 - other common code

@constructor
@author SAP SE
@alias sap.ui.webc.main.CalendarPart
@extends sap.ui.webc.main.DateComponentBase
@public