Liberty app accelerator has been taken down.
You can still generate Liberty applications for the cloud through IBM Cloud Developer tools or IBM Cloud UI .
The Liberty starters provided by Liberty app accelerator have been uploaded to Maven Central and can still be used in your projects.
Liberty and IBM Cloud

Copyright (c) 2015, 2018 IBM Corp. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at www.apache.org/licenses/LICENSE-2.0.

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License.