Example test case showing the bug I described in INT-3448. Enabling Spring
async support when a service interface has an @Async method produces a
NullPointerException on invocation.
To run this test case, run as a Spring Boot app from STS or run the
generated jar. Issue a GET request to /do/{argument}. The test case works
properly if the @EnableAsync annotation is commented out of the configuration
in Launcher.