private void createAndStartupRegistry() {
    if (registry != null) return;

    RegistryBuilder builder = new RegistryBuilder();
    builder.add(ExtensionModule.class);
    for (Class<?> module : modules) builder.add(module);
    registry = builder.build();
    registry.performRegistryStartup();
  }
Controls creation, startup and shutdown of the Tapestry container,
and injects specifications with Tapestry-provided objects.

@author Peter Niederwieser
spock-tapestry/src/main/java/org/spockframework/tapestry/TapestryInterceptor.java