@Override
  public <T> T getConfigurationByType(Class<T> clazz) {
    return clazz.cast(configurationsByType.get(clazz));
  }
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