Example 24.14 from Chapter 24 of User Docs not working

I have (really, this time) replicated the project structure documented here:


…and when I run the documented command line (using the gradle wrapper), I get this error:

$ ./gradlew -q action

FAILURE: Build failed with an exception.

* Where:
Build file 'C:\Users\Hoobajoob\messages\consumer\build.gradle' line: 2

* What went wrong:
Execution failed for task ':consumer:action'.
> Could not find property 'producerMessage' on root project 'messages'.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

…but the documentation claims I should be getting this result:

> gradle -q action
Consuming message: null
Producing message:

Is the documentation out of date? Or, does it require version 2.13? I’m using 2.12.

Ah - the User Guide is missing the root project’s build.gradle file.

That can be found here:

…and looky what it contains!

ext.producerMessage = null