/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/ 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/maildir/MaildirFolder.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/MaildirMessage.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/MaildirStore.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/class-use/
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/class-use/MaildirFolder.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/class-use/MaildirMessage.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/class-use/MaildirStore.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/package-frame.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/package-summary.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/package-tree.html
/usr/share/doc/libgnumail-java/api/gnu/mail/providers/maildir/package-use.html