The Instant class represents an instant in time.
It is an ideal object for storing time-stamps of log events.
For example, the instant of an event such as saving a file to GitHub can be recorded in an Instant.
The time-line of human experience consists of a continuous set of instants.
In ThreeTen, these instants can be recorded at nanosecond precision in the Instant class.
Creating an Instant
There are a number of ways to create an Instant.
Now
Creating the current instant is achieved using one of the now methods:
Instant a = Instant.now();
Instant b = Instant.now(aClock);The first method (a) obtains the current instant from the system clock, which is a wrapper
around System.currentTimeMillis().
The second method (b) uses a Clock object to provide further control over the current instant.
