chg: check if the stix2 file is from MISP export
chg: check if the stix2 file is from MISP export

SteveClement/MISP,MISP/MISP,TheDr1ver/MISP,devnull-/MISP,FloatingGhost/MISP,TheDr1ver/MISP,FloatingGhost/MISP,SteveClement/MISP,SteveClement/MISP,devnull-/MISP,SteveClement/MISP,MISP/MISP,Rafiot/MISP,SteveClement/MISP,FIRSTdotorg/MISP,FIRSTdotorg/MISP,TheDr1ver/MISP,FloatingGhost/MISP,FIRSTdotorg/MISP,MISP/MISP,FIRSTdotorg/MISP,Rafiot/MISP,MISP/MISP,Rafiot/MISP,devnull-/MISP,TheDr1ver/MISP,MISP/MISP,Rafiot/MISP,devnull-/MISP,FloatingGhost/MISP