private JibMavenPluginExtension<?> findConfiguredExtension(
      List<JibMavenPluginExtension<?>> extensions, ExtensionConfiguration config)
      throws JibPluginExtensionException {
    Predicate<JibMavenPluginExtension<?>> matchesClassName =
        extension -> extension.getClass().getName().equals(config.getExtensionClass());
    Optional<JibMavenPluginExtension<?>> found =
        extensions.stream().filter(matchesClassName).findFirst();
    if (!found.isPresent()) {
      throw new JibPluginExtensionException(
          NullExtension.class,
          "extension configured but not discovered on Jib runtime classpath: "
              + config.getExtensionClass());
    }
    return found.get();
  }
Returns Spring Boot {@code <configuration>} if the Spring Boot plugin is configured to run the
{@code repackage} goal to create a Spring Boot artifact.
jib-maven-plugin/src/main/java/com/google/cloud/tools/jib/maven/MavenProjectProperties.java