/usr/include/ql/experimental/credit/ is in libquantlib0-dev 1.7.1-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ql/experimental/credit/all.hpp
/usr/include/ql/experimental/credit/basecorrelationlossmodel.hpp
/usr/include/ql/experimental/credit/basecorrelationstructure.hpp
/usr/include/ql/experimental/credit/basket.hpp
/usr/include/ql/experimental/credit/binomiallossmodel.hpp
/usr/include/ql/experimental/credit/blackcdsoptionengine.hpp
/usr/include/ql/experimental/credit/cdo.hpp
/usr/include/ql/experimental/credit/cdsoption.hpp
/usr/include/ql/experimental/credit/constantlosslatentmodel.hpp
/usr/include/ql/experimental/credit/correlationstructure.hpp
/usr/include/ql/experimental/credit/defaultevent.hpp
/usr/include/ql/experimental/credit/defaultlossmodel.hpp
/usr/include/ql/experimental/credit/defaultprobabilitykey.hpp
/usr/include/ql/experimental/credit/defaultprobabilitylatentmodel.hpp
/usr/include/ql/experimental/credit/defaulttype.hpp
/usr/include/ql/experimental/credit/distribution.hpp
/usr/include/ql/experimental/credit/factorspreadedhazardratecurve.hpp
/usr/include/ql/experimental/credit/gaussianlhplossmodel.hpp
/usr/include/ql/experimental/credit/homogeneouspooldef.hpp
/usr/include/ql/experimental/credit/inhomogeneouspooldef.hpp
/usr/include/ql/experimental/credit/integralcdoengine.hpp
/usr/include/ql/experimental/credit/integralntdengine.hpp
/usr/include/ql/experimental/credit/issuer.hpp
/usr/include/ql/experimental/credit/loss.hpp
/usr/include/ql/experimental/credit/lossdistribution.hpp
/usr/include/ql/experimental/credit/midpointcdoengine.hpp
/usr/include/ql/experimental/credit/nthtodefault.hpp
/usr/include/ql/experimental/credit/onefactorcopula.hpp
/usr/include/ql/experimental/credit/onefactorgaussiancopula.hpp
/usr/include/ql/experimental/credit/onefactorstudentcopula.hpp
/usr/include/ql/experimental/credit/pool.hpp
/usr/include/ql/experimental/credit/randomdefaultlatentmodel.hpp
/usr/include/ql/experimental/credit/randomdefaultmodel.hpp
/usr/include/ql/experimental/credit/randomlosslatentmodel.hpp
/usr/include/ql/experimental/credit/recoveryratemodel.hpp
/usr/include/ql/experimental/credit/recoveryratequote.hpp
/usr/include/ql/experimental/credit/recursivelossmodel.hpp
/usr/include/ql/experimental/credit/riskyassetswap.hpp
/usr/include/ql/experimental/credit/riskyassetswapoption.hpp
/usr/include/ql/experimental/credit/riskybond.hpp
/usr/include/ql/experimental/credit/saddlepointlossmodel.hpp
/usr/include/ql/experimental/credit/spotlosslatentmodel.hpp
/usr/include/ql/experimental/credit/spreadedhazardratecurve.hpp
/usr/include/ql/experimental/credit/syntheticcdo.hpp