code: private PeriodList getConsumedTime(final ComponentList<CalendarComponent> components, final DateTime rangeStart,
              final DateTime rangeEnd) {
          
          final PeriodList periods = new PeriodList();
          // only events consume time..
          for (final Component event : components.getComponents(Component.VEVENT)) {
              periods.addAll(((VEvent) event).getConsumedTime(rangeStart, rangeEnd, false));
          }
          return periods.normalise();
      }
docs: Creates a list of periods representing the time consumed by the specified list of components.
  @param components
  @return