missing "getPositionQuadraticApproximation" method?

[hsqthu2012]

Hi, I was trying to run foot placement test in this repo. But I found out that the method getPositionQuadraticApproximation in the following is missing.
https://github.com/matheecs/ocs2_legged_robot_annotated/blob/c7f56cc191a07f2bc44629de81132e541f7d45c7/src/constraint/FootPlacementConstraint.cpp#L152
I've browsed the code in OCS2 but there is only getPositionLinearApproximation method.
Without the getPositionQuadraticApproximation method, the compile will fail. Thus I'm wondering where can I find this method?

Thanks!