// version skew drop back to resolution from the repository
                    return null;
                }

                // Validate versions aren't inherited when using parent ranges the same way as when read externally.
                String rawChildModelVersion = childModel.getVersion();

                if (rawChildModelVersion == null) {

            // a task to finish, then execute another one which waits
            // for the initial task...
            // In order to work around that problem, we override the
            // invokeAll method, so that whenever the method is called,
            // the pool core size will be incremented before submitting
            // all the tasks, then the thread will block waiting for all