Propagation with additional equations in v11.1.2
this is the issue related to this discussion on the forum.
Until now, Orekit allowed considering the effects of secondary states on the main states derivatives by simply returning an array instead of null in the AdditionalEquations.computeDerivatives method. This array was then used to update the primary state derivatives.
However, the recent changes in Orekit v11.1.2 have removed this possibility, as the primary derivatives are not updated anymore.