/usr/include/ace/HTBP/ is in libace-htbp-dev 6.4.5+dfsg-1build2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/ace/HTBP/HTBP_Addr.h
/usr/include/ace/HTBP/HTBP_Channel.h
/usr/include/ace/HTBP/HTBP_Channel.inl
/usr/include/ace/HTBP/HTBP_Environment.h
/usr/include/ace/HTBP/HTBP_Export.h
/usr/include/ace/HTBP/HTBP_Filter.h
/usr/include/ace/HTBP/HTBP_Filter.inl
/usr/include/ace/HTBP/HTBP_Filter_Factory.h
/usr/include/ace/HTBP/HTBP_ID_Requestor.h
/usr/include/ace/HTBP/HTBP_Inside_Squid_Filter.h
/usr/include/ace/HTBP/HTBP_Inside_Squid_Filter.inl
/usr/include/ace/HTBP/HTBP_Macros.h
/usr/include/ace/HTBP/HTBP_Notifier.h
/usr/include/ace/HTBP/HTBP_Outside_Squid_Filter.h
/usr/include/ace/HTBP/HTBP_Outside_Squid_Filter.inl
/usr/include/ace/HTBP/HTBP_Session.h
/usr/include/ace/HTBP/HTBP_Session.inl
/usr/include/ace/HTBP/HTBP_Stream.h