/usr/include/libxml++-2.6/libxml++/nodes/ is in libxml++2.6-dev 2.36.0-2ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/libxml++-2.6/libxml++/nodes/cdatanode.h
/usr/include/libxml++-2.6/libxml++/nodes/commentnode.h
/usr/include/libxml++-2.6/libxml++/nodes/contentnode.h
/usr/include/libxml++-2.6/libxml++/nodes/element.h
/usr/include/libxml++-2.6/libxml++/nodes/entitydeclaration.h
/usr/include/libxml++-2.6/libxml++/nodes/entityreference.h
/usr/include/libxml++-2.6/libxml++/nodes/node.h
/usr/include/libxml++-2.6/libxml++/nodes/processinginstructionnode.h
/usr/include/libxml++-2.6/libxml++/nodes/textnode.h
/usr/include/libxml++-2.6/libxml++/nodes/xincludeend.h
/usr/include/libxml++-2.6/libxml++/nodes/xincludestart.h