/usr/include/pluma/ is in pluma-dev 1.8.1+dfsg1-2.
This file is owned by root:root, with mode 0o755.
..
/usr/include/pluma/pluma-app.h
/usr/include/pluma/pluma-commands.h
/usr/include/pluma/pluma-debug.h
/usr/include/pluma/pluma-document.h
/usr/include/pluma/pluma-encodings-combo-box.h
/usr/include/pluma/pluma-encodings.h
/usr/include/pluma/pluma-file-chooser-dialog.h
/usr/include/pluma/pluma-help.h
/usr/include/pluma/pluma-message-bus.h
/usr/include/pluma/pluma-message-type.h
/usr/include/pluma/pluma-message.h
/usr/include/pluma/pluma-notebook.h
/usr/include/pluma/pluma-panel.h
/usr/include/pluma/pluma-plugin.h
/usr/include/pluma/pluma-prefs-manager-app.h
/usr/include/pluma/pluma-prefs-manager.h
/usr/include/pluma/pluma-progress-message-area.h
/usr/include/pluma/pluma-status-combo-box.h
/usr/include/pluma/pluma-statusbar.h
/usr/include/pluma/pluma-tab.h
/usr/include/pluma/pluma-utils.h
/usr/include/pluma/pluma-view.h
/usr/include/pluma/pluma-window.h