SpanGaps in LineChartDataset

[lizziebeans]

Hello, I'm a little confused as to how SpanGaps works.
From the documentation:

If true, lines will be drawn between points with no or null data. If false, points with null data will create a break in the line. Can also be a number specifying the maximum gap length to span. The unit of the value depends on the scale used.

But a single data point can never be null due to the type in LineChartDataset

As far as I can tell - the X-axis is defined from ChartData.Labels which is just a list of strings.
Then each LineChartDataSet has a Data property which is just a list of doubles whose length should match the amount of labels.
Unless I'm mistaken, there doesn't seem to be any scope to create gaps?