This is perfectly legal for JavaDoc (please see previous issue linked below) but the bug has to deal with how Gradle handles text strings here. Similar bug reports were submitted in the past but only a partially fix was created. My current work around is still to use Ant to create javadoc.
Tested with Gradle 2.9 , jdk1.8.0_65/ , Mint Linux 17.2
Yes and no. I’m over booked. Trying to off load programming in a similar
fashion on my own open source projects, with very limited success. So if
no one fixes it I might give it a shot in 1 to 3 months.