Accessing ScalaFX chart axis extreme values

Question

I'm building a regression visualiser and can plot the original data and calculate the regression model. For fitting, I'd like to include predictions for the whole chart axis range available, not only the original data range.

Creating the empty chart sets xAxis 0 to 110 by default.

Then I'm plotting the data:

How can I access the visible xAxis extreme values, and especially the upper 5.5?

Trying xAxis.getUpperBound gives the original 110.