Summary

Add -source and -target and --release options to javac corresponding to JDK 18.

Problem

Part of starting development on a new JDK is adding .new -source and -target options to javac. These options are used in the compilation of the JDK sources.

Solution

Add 18 as a valid argument to the options in question.

Specification

Add support for javac -source 18 ..., and javac -target 18 ..., and javac --release 18 ....

The new value of -source/-target is also made the default.

As a consequence of adding support for the new argument to javac, support is also added to javadoc and the java --source option.