Returns time in milliseconds as does System.currentTimeMillis(),
but uses elapsed time from an arbitrary epoch more like System.nanoTime().
The difference is that if somebody changes the system clock,
Time.currentElapsedTime will change but nanoTime won't. On the other hand,
all of ZK assumes that time is measured in milliseconds.
The time in milliseconds from some arbitrary point in time.
public static long currentWallTime()
Explicitly returns system dependent current wall time.
Current time in msec.
public static Date elapsedTimeToDate(long elapsedTime)