@Test
  public void testRunPluginExtensions_noExtensionsConfigured() throws JibPluginExtensionException {
    FooExtension extension =
        new FooExtension((buildPlan, properties, extraConfig, mavenData, logger) -> buildPlan);
    loadedExtensions = Arrays.asList(extension);

    JibContainerBuilder extendedBuilder =
        mavenProjectProperties.runPluginExtensions(Collections.emptyList(), containerBuilder);
    Assert.assertSame(extendedBuilder, containerBuilder);

    mavenProjectProperties.waitForLoggingThread();
    Mockito.verify(mockLog).debug("No Jib plugin extensions configured to load");
  }
Plugin extension test for {@link MavenProjectProperties}.
jib-maven-plugin/src/test/java/com/google/cloud/tools/jib/maven/MavenProjectPropertiesExtensionTest.java