Various other things use TestApplication in core's src/test/java, by doing:

        <dependency>
            <groupId>io.brooklyn</groupId>
            <artifactId>brooklyn-core</artifactId>
            <version>${project.version}</version>
            <classifier>tests</classifier>
            <scope>test</scope>
        </dependency>

Probably not worth adding this for just core's TestApplication, but worth bearing in mind if we want other test things...