code: public boolean isEquivalentTo(Calendar other) {
          return this.getClass() == other.getClass() &&
                  isLenient() == other.isLenient() &&
                  getFirstDayOfWeek() == other.getFirstDayOfWeek() &&
                  getMinimalDaysInFirstWeek() == other.getMinimalDaysInFirstWeek() &&
                  getTimeZone().equals(other.getTimeZone()) &&
                  getRepeatedWallTimeOption() == other.getRepeatedWallTimeOption() &&
                  getSkippedWallTimeOption() == other.getSkippedWallTimeOption();
      }
docs: <strong>[icu]</strong> Returns true if the given Calendar object is equivalent to this
  one.  An equivalent Calendar will behave exactly as this one
  does, but it may be set to a different time.  By contrast, for
  the equals() method to return true, the other Calendar must
  be set to the same time.
  
  @param other the Calendar to be compared with this Calendar