The jdk.test.lib.process.ProcessTools.createJavaProcessBuilder API is inconvenient when you want to pass some arguments only under certain conditions. You either have to build an ArrayList of arguments, or do hacks like this

ProcessTools.createJavaProcessBuilder("-cp", "foobar",
    Platform.isDebugBuild() ? "-XX:-VerifyDependencies" : "-Dx",
    "TestApp");

This RFE proposes an enhancement to the API, so you can do things like:

ProcessTools.createJavaProcessBuilder("-cp", "foobar",
    ifDebug.use("-XX:-VerifyDependencies"),
    "TestApp");

ProcessTools.createJavaProcessBuilder("-cp", "foobar",
    "TestApp",
     ifCond(x == 0).use("x", "is", "zero").orElse().use("not", "zero"));

Note that the second example cannot be done with the current API. I.e., something like the following is not valid Java syntax.

ProcessTools.createJavaProcessBuilder("-cp", "foobar",
    "TestApp",
     (x == 0) ? {"x", "is", "zero"} : {"not", "zero"});

See attachment for a rough draft of the proposal