private boolean isRepeatableExtensionAnnotation(AnnotationNode annotation) {
    ClassNode annotationClass = annotation.getClassNode();
    return hasAnnotation(annotationClass, ExtensionAnnotation.class) &&
      hasAnnotation(annotationClass, Repeatable.class);
  }
Puts all spec information required at runtime into annotations
attached to class members.

@author Peter Niederwieser
spock-core/src/main/java/org/spockframework/compiler/SpecAnnotator.java