Event Grid output binding does not work on Java

[johndowns]

In the process of updating the documentation for the Event Grid output binding (see this PR), I discovered that the output binding does not work correctly with Java functions. It does work correctly for .NET and Node.js. (Note I have opened a separate issue to log that this doesn't work for Python either.)

• I wasn't able to get a test function working for the Event Grid output binding. I can see the trigger binding works - this problem is specifically about the output binding.
• However I can see that for the trigger, there is a Java annotation in the Azure Functions Java library, so I assume something similar would be needed here too.
• Also, as documented on the Python issue the bundle looks like it hasn't been updated to include the Event Grid output binding.