/usr/share/glib-2.0/schemas/ is in gnome-builder 3.28.1-1ubuntu1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/glib-2.0/schemas/org.gnome.builder.build.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.code-insight.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.editor.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.editor.language.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.extension-type.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.gnome-code-assistance.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.plugin.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.plugins.color_picker_plugin.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.plugins.eslint.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.project-tree.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.project.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.terminal.gschema.xml
/usr/share/glib-2.0/schemas/org.gnome.builder.workbench.gschema.xml