private Object getInjectionParameter(Parameter parameter, Class<?> extensionClass) {
    ConfigurationObject annotation = parameter.getType().getAnnotation(ConfigurationObject.class);
    return getOrCreateConfig(parameter.getType(), annotation, extensionClass);
  }
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