private Object createAndStoreConfiguration(Class<?> configuration, ConfigurationObject annotation) {
    Object instance = createConfiguration(configuration);
    configurationsByType.put(configuration, instance);
    configurationsByName.put(annotation.value(), instance);
    return instance;
  }
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