Java build systems (Ant, Maven, Gradle) used to require "java-devel"
because their typical usages involves code compilation, which requires
full JDK.
In Fedora 23 I've just replaced hard requirement on "java-devel" with
recommends. From now on Ant, Maven and Gradle require "java-headlesss"
and recommend "java-devel", which means that by default they will still
be installed with full JDK, but it will be possible to install and use
them with just headless JRE.
--
Mikolaj Izdebski
Software Engineer, Red Hat
IRC: mizdebsk