To backport would take me too much time.
We have not sufficient ressource to afford to maintain two FESAPI versions at the same time. Please ask other vendors to support the standard, not a subset of it.
A workaround is a bit explained into the issue :
Workaround, call the SWIG implementation of the WellboreMarkers instead of the CPP-like constructor and set the last parameter to false instead of true.
It would mean to call
WellboreMarker marker0 = new WellboreMarker(fesapiJNI.new_resqml2_0_1_WellboreMarker__SWIG_1(WellboreMarkerFrameRepresentation.getCPtr(wmf), wmf, "624f9f17-6797-4d78-b3fc-9ca2c8174bcd",
"", resqml20__GeologicBoundaryKind.horizon.swigValue()), false);
instead of
WellboreMarker marker0 = new WellboreMarker(wmf, "624f9f17-6797-4d78-b3fc-9ca2c8174bcd", "", gsoap_resqml2_0_1::resqml20__GeologicBoundaryKind__horizon);
I hope this workaround would work.