OPA-E00476 Java 7 or later is required to run the embedded web server.
I had to update to OPA May 2017 recently, and today, I got a Java update notice. I was behind, and Java updates are (usually...) harmless, so I updated to Java 8 Update 144. I can see in Control Panel > Programs and Features that it's installed. Now I get an error when I try to launch the debugger.
Oracle Policy Modeling
The debugger is not available: Java 7 or later is required to run the embedded web server. Java 0 () was found. (OPA-E00476)