There is no longer a separate hotspot version in jdk9, so the version string produced by java -version and java -Xinternalversion must be updated.

Promoted builds should simply match the version and build number
of the JDK. Development builds should include the jdk version
and build number upon which the source is based, plus an
additional indicator that there are additional changes (e.g., a
hash/id from the source code management tool or a datestamp).

Promoted build:

java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b01)
Java HotSpot(TM) Server VM (build 1.9.0-ea-b01, mixed mode)

Developer build, when mercurial is available:

java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b01)
Java HotSpot(TM) Server VM (build 1.9.0-ea-b01+0e1d2038c219, mixed mode)

Developer build, when mercurial is not available:

java version "1.9.0-ea"
Java(TM) SE Runtime Environment (build 1.9.0-ea-b01)
Java HotSpot(TM) Server VM (build 1.9.0-ea-b01+20140101-133914, mixed mode)