@Override
public Period clone() {
Period newPeriod;
try {
newPeriod = (Period) super.clone();
} catch (final CloneNotSupportedException e) {
// this should never happen, since it is Cloneable
throw new InternalError(e.getMessage());
}
newPeriod.begin = begin == null ? null : (Calendar) begin.clone();
newPeriod.end = end == null ? null : (Calendar) end.clone();
return newPeriod;
}
