code: public LocalDateTime toLocalDateTime(LocalTime time) {
          if (time == null) {
              throw new IllegalArgumentException("The time must not be null");
          }
          if (getChronology() != time.getChronology()) {
              throw new IllegalArgumentException("The chronology of the time does not match");
          }
          long localMillis = getLocalMillis() + time.getLocalMillis();
          return new LocalDateTime(localMillis, getChronology());
      }
docs: Converts this object to a LocalDateTime using a LocalTime to fill in
  the missing fields.
  <p>
  The resulting chronology is determined by the chronology of this
  LocalDate. The chronology of the time must also match.
  If the time is null an exception is thrown.
  <p>
  This instance is immutable and unaffected by this method call.
  
  @param time  the time of day to use, must not be null
  @return the LocalDateTime instance
  @throws IllegalArgumentException if the time is null
  @throws IllegalArgumentException if the chronology of the time does not match
  @since 1.5