/usr/include/pwiz/pwiz/analysis/demux/ is in libpwiz-dev 3.0.10827-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/pwiz/pwiz/analysis/demux/CubicHermiteSpline.hpp
/usr/include/pwiz/pwiz/analysis/demux/DemuxDebugReader.hpp
/usr/include/pwiz/pwiz/analysis/demux/DemuxDebugWriter.hpp
/usr/include/pwiz/pwiz/analysis/demux/DemuxHelpers.hpp
/usr/include/pwiz/pwiz/analysis/demux/DemuxSolver.hpp
/usr/include/pwiz/pwiz/analysis/demux/DemuxTypes.hpp
/usr/include/pwiz/pwiz/analysis/demux/EnumConstantNotPresentException.hpp
/usr/include/pwiz/pwiz/analysis/demux/IDemultiplexer.hpp
/usr/include/pwiz/pwiz/analysis/demux/IInterpolation.hpp
/usr/include/pwiz/pwiz/analysis/demux/IPrecursorMaskCodec.hpp
/usr/include/pwiz/pwiz/analysis/demux/MSXDemultiplexer.hpp
/usr/include/pwiz/pwiz/analysis/demux/MatrixIO.hpp
/usr/include/pwiz/pwiz/analysis/demux/OverlapDemultiplexer.hpp
/usr/include/pwiz/pwiz/analysis/demux/PrecursorMaskCodec.hpp
/usr/include/pwiz/pwiz/analysis/demux/SpectrumPeakExtractor.hpp