In JDK 9, there are eight module based directories termed as repos.
root
corba
hotspot
jaxp
jaxws
jdk
langtools
nashorn
Code is organized like −
$ROOT/jdk/src/java.base ... $ROOT/langtools/src/java.compiler ...
Java 10 onwards, JDK forests are organized into single repository to streamline development. Now code in organized as -
$ROOT/src/java.base $ROOT/src/java.compiler ...