public static Iterator<Object> asIterator(Object object) {
    try {
      return InvokerHelper.asIterator(object);
    } catch (InvokerInvocationException e) {
      return ExceptionUtil.sneakyThrow(e.getCause());
    }
  }
Note: This method may throw checked exceptions although it doesn't say so.
spock-core/src/main/java/org/spockframework/runtime/GroovyRuntimeUtil.java