/usr/include/gegl-0.3/operation/ is in libgegl-dev 0.3.8-4.
This file is owned by root:root, with mode 0o755.
..
/usr/include/gegl-0.3/operation/gegl-extension-handler.h
/usr/include/gegl-0.3/operation/gegl-operation-area-filter.h
/usr/include/gegl-0.3/operation/gegl-operation-composer.h
/usr/include/gegl-0.3/operation/gegl-operation-composer3.h
/usr/include/gegl-0.3/operation/gegl-operation-context.h
/usr/include/gegl-0.3/operation/gegl-operation-filter.h
/usr/include/gegl-0.3/operation/gegl-operation-handlers.h
/usr/include/gegl-0.3/operation/gegl-operation-meta-json.h
/usr/include/gegl-0.3/operation/gegl-operation-meta.h
/usr/include/gegl-0.3/operation/gegl-operation-point-composer.h
/usr/include/gegl-0.3/operation/gegl-operation-point-composer3.h
/usr/include/gegl-0.3/operation/gegl-operation-point-filter.h
/usr/include/gegl-0.3/operation/gegl-operation-point-render.h
/usr/include/gegl-0.3/operation/gegl-operation-property-keys.h
/usr/include/gegl-0.3/operation/gegl-operation-sink.h
/usr/include/gegl-0.3/operation/gegl-operation-source.h
/usr/include/gegl-0.3/operation/gegl-operation-temporal.h
/usr/include/gegl-0.3/operation/gegl-operation.h