The default build for JT Harness 4.6 uses v49 class files, which can run on JDK 5.

The default build for JT Harness 5.0 uses v51 class files, which requires the use of JDK 7.

We still want to be able to use jtreg on old versions of the platform, and currently, this is blocking the adoption of JT Harness 5. But JT Harness 5 is desirable in its own right, because it has no dependence on JavaHelp, meaning that JavaHelp does not need to be available when building jtreg and on the classpath when running it.

The jtreg classes that may be used in the test VM have been refactored into their own package, com.sun.javatest.regtest.agent. Analysing the imports of those classes reveal that the following classes depend on JT Harness classes:

src/share/classes/com/sun/javatest//regtest/agent/AppletWrapper.java
src/share/classes/com/sun/javatest//regtest/agent/RegressionSecurityManager.java
src/share/classes/com/sun/javatest//regtest/agent/MainActionHelper.java
src/share/classes/com/sun/javatest//regtest/agent/RStatus.java
src/share/classes/com/sun/javatest//regtest/agent/CompileActionHelper.java
src/share/classes/com/sun/javatest//regtest/agent/ActionHelper.java
src/share/classes/com/sun/javatest//regtest/agent/AgentServer.java
src/share/classes/com/sun/javatest//regtest/agent/Alarm.java
src/share/classes/com/sun/javatest//regtest/agent/RegressionCompileCommand.java

And the classes used are:

com.sun.javatest.Command
com.sun.javatest.JavaTestSecurityManager
com.sun.javatest.Status
com.sun.javatest.TestResult
com.sun.javatest.util.I18NResourceBundle
com.sun.javatest.util.PathClassLoader
com.sun.javatest.util.WriterStream

Many of these are effectively references from dead/unused code. We should work to reduce this list as much as possible.