cdm/src/main/java/ucar/nc2/units/DateRange.java
public void setStart(DateType start) {
    this.start = start;
    useStart = true;

    if (useEnd) {
      this.isMoving = this.start.isPresent() || this.end.isPresent();
      useDuration = false;
      recalcDuration();

    } else {
      this.isMoving = this.start.isPresent();
      this.end = this.start.add(duration);
    }
    checkIfEmpty();
  }
public void setStart(DateType start) {
    this.start = start;
    useStart = true;

    if (useEnd) {
      this.isMoving = this.start.isPresent() || this.end.isPresent();
      useDuration = false;
      recalcDuration();

    } else {
      this.isMoving = this.start.isPresent();
      this.end = this.start.add(duration);
    }
    checkIfEmpty();
  }
Set the starting Date. Makes useStart true.
If useEnd, recalculate the duration, else recalculate end.

@param start starting Date