MarsSeed [1] filed a deletion request for jdk-devel-docs [2]:
Addon documents package for the defunct 'jdk-devel' package (Oracle Java 11 Development Kit preview version).
Both packages are orphaned and source is behind Oracle paywall.
Both 'jdk-devel' and 'jdk-devel-docs' names are confusingly too broad because of legacy reasons. These are not based on OpenJDK but on Oracle's version of JDK.
I think it is not useful to keep this package. Oracle insider access subscribers can likely download / access the non-public documentation already, without this defunct package.
Also the majority of the development is not done by Oracle behind closed doors, but by a collaborative open-source community (OpenJDK). Maybe that's the reason for the limited and diminished interest for this Oracle-based package during the last few years.
[1] https://aur.archlinux.org/account/MarsSeed/ [2] https://aur.archlinux.org/pkgbase/jdk-devel-docs/