/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/ is in libgnumail-java-doc 1.1.2-7.
This file is owned by root:root, with mode 0o755.
..
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/POP3Folder.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/POP3Message.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/POP3Store.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/class-use/
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/class-use/POP3Folder.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/class-use/POP3Message.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/class-use/POP3Store.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/package-frame.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/package-summary.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/package-tree.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/pop3/package-use.html