/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/ is in libplexus-containers-java-doc 1.0~beta3.0.7-7.
This file is owned by root:root, with mode 0o755.
..
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/PlexusConfigurationReader.html
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/PlexusConfigurationWriter.html
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/XmlPlexusConfigurationReader.html
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/XmlPlexusConfigurationWriter.html
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/package-frame.html
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/package-summary.html
/usr/share/doc/libplexus-containers-java/api/org/codehaus/plexus/configuration/io/package-tree.html