Weird global config `_cartographicRadians` and doc for `Ellipsoid.cartesianToCartographic` is not clear

[zengfenfei]

I try to use Ellipsoid.cartesianToCartographic, and refer to the API reference, but it does not tell me the order of cartographic array and wether it's degree or radians:

Then I find the another example, which tell me the order of the cartographic parameter and the unit is radian:

But when I run the code, I realize the cartographic unit is not radian by default, it's controlled by a global config _cartographicRadians which has a weird name that starts with an underscore. I don't understand the ideas behind.