/usr/share/mrpt/config_files/graphslam-engine/ is in mrpt-common 1:1.5.5-1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/mrpt/config_files/graphslam-engine/doxygen_config_files/
/usr/share/mrpt/config_files/graphslam-engine/doxygen_config_files/config_params_preamble.txt
/usr/share/mrpt/config_files/graphslam-engine/doxygen_config_files/graphslam-engine_config_params_preamble.txt
/usr/share/mrpt/config_files/graphslam-engine/laser_odometry.ini
/usr/share/mrpt/config_files/graphslam-engine/laser_odometry_LC.ini
/usr/share/mrpt/config_files/graphslam-engine/odometry_2DRangeScans.ini
/usr/share/mrpt/config_files/graphslam-engine/odometry_2DRangeScans_LC.ini
/usr/share/mrpt/config_files/graphslam-engine/odometry_3d_slam.ini
/usr/share/mrpt/config_files/graphslam-engine/rgbd_datasets.ini