fadeSteps property
Controls how the alarm volume will fade over time.
Set to empty list by default, which means no fade.
Example:
fadeStopTimes = 0s, 10s, 20s
fadeStopVolumes = 0, 0.5, 1.0
The alarm will begin silent, fade to 50% of max volume by 10 seconds,
and fade to max volume by 20 seconds.
Implementation
final List<VolumeFadeStep> fadeSteps;