Ability to get the earliest and latest sample in a SamplePositionProperty

[c3-victor-mao]

Feature

Feature Request: methods that allow user to get the earliest and latest sample in a SamplePositionProperty.

Following the SampledPositionProperty docs, I can add samples and get the interpolated position at a given time, but after adding the samples, I'm having a hard time being able to get the earliest and latest sample information to set the Cesium Clock startTime and endTime.

Wondering if others think this sounds like a potentially useful feature?

[ggetz]

Thanks for the request @c3-victor-mao. Is this something you would consider contributing?