How to produce business rule output that can be examined in the ODM Rule Execution Server Console?

I am new to ODM 8.5 (the successor to JRules), and I am trying to test some rules in the ODM Rule Execution Server Console. At this point, I'm merely trying to confirm that my rule changes have been deployed to the RES successfully. According to ODM's Testing Ruleset Execution help page, I should be able to examine the Output text box to see "strings that are written to print.out" from the web page under Explorer > RuleApps > RuleApp > Ruleset > Test Ruleset. I've deployed a rule containing the following snippet:

However, after executing the rule, I don't see the output of the println in the Output box. Is println what the documentation refers to when they say "print.out"? I get syntax errors if I try to replace "System.out.println" with "print.out". How can I get simple debug output to appear in the Output box?

The note method will cause output to go to the Output text box of the ODM Rule Execution Server Console, e.g., use:

note("*** This is the rule modification ***");