private Object getOrCreateConfiguration(Class<?> type, ConfigurationObject annotation) {
    Object config = getConfigurationByType(type);
    if (config == null) {
      config = createAndStoreConfiguration(type, annotation);
    }
    return config;
  }
Maintains a registry of global Spock extensions and their configuration objects,
which can be used to configure other extensions.

@author Peter Niederwieser
spock-core/src/main/java/org/spockframework/runtime/GlobalExtensionRegistry.java