Instances of this class represent values so immutable objects are used. In order to do modifications new instances must be created.
A date type that represents a point inside a working day. This doesn't translate directly to a concrete DateTime because the working day can start at an arbitrary hour.
It represents the instant at which {@link #effortDuration} has been elapsedin the working day specified by the field {@link #date}. Since the amount of time for a working day is measured with an {@link EffortDuration}, to indicate the point inside a working day an {@link EffortDuration} isspecified.
For example, a IntraDayDate with a date such as 23/07/2010 and an effort duration of 2 hours represents the moment on 23/07/2010 at which 2 hours of the working day had been elapsed. Normally this object can't be converted to a precise {@link DateTime} due to not knowing the timetable of the workers.Nevertheless, this object is useful anyway in order to know how many effort is left at the working day.
@see PartialDay
@see LocalDate
@see EffortDuration
@author Óscar González Fernández
@author Manuel Rego Casasnovas