Duration
A measurement of time. Durations may be positive, zero, or negative.
Positive durations are measured in seconds, with both #getSeconds and #getNano parts with non-negative signs.
Negative durations may be surprising. The #getSeconds property is negative, but the #getNano property is non-negative! To represent -1.3 seconds the seconds property is -2 and the nanos property is 700,000,000.