static String loadDefaultConfigGenVersion() throws MojoExecutionException {
        Properties props = new Properties();
        try {
            props.load(GenerateSourcesMojo.class.getResourceAsStream("/build.properties"));
        } catch (IOException e) {
            throw new MojoExecutionException("Failed to resolve version of com.yahoo.vespa:config-class-plugin.",
                                             new FileNotFoundException("/build.properties"));
        }
        return props.getProperty("projectVersion");
    }
@Test
    void requireThatDefaultConfigGenVersionIsLoadedFromBuildProperties() throws MojoExecutionException {
        String expected = System.getProperty("expectedDefaultConfigGenVersion");
        System.out.println("expectedDefaultConfigGenVersion = " + expected);
        assumeTrue(expected != null);

        String actual = GenerateSourcesMojo.loadDefaultConfigGenVersion();
        System.out.println("defaultConfigGenVersion = " + actual);
        assertEquals(expected, actual);
    }