Revert the design choice for the existing FootprintOverlapDetector
This issue is related to the following discussion https://forum.orekit.org/t/created-sphericalpolygonset-gives-nullpointerexception-with-footprintoverlapdetectorh/1251/8
This issue is related to the following discussion https://forum.orekit.org/t/created-sphericalpolygonset-gives-nullpointerexception-with-footprintoverlapdetectorh/1251/8