code: public boolean openAt(@NotNull final HourRange range) {
          Contract.requireArgNotNull("range", range);
          return hourRanges.openAt(range);
      }
docs: Determines if this instance if "open" at the given time range. It is only allowed to call this method if the hour ranges represents
  only one day. This means a value like '18:00-03:00' will lead to an error. To avoid this, call the {@link #normalize()} function
  before this one and pass the result per day as an argument to this method.
  
  @param range
  Time range to verify.
  
  @return {@literal true} if open else {@literal false} if not open.