com/android/support/design-button/maven-metadata.xml

<?xml version="1.0" encoding="UTF-8"?>
<metadata>
  <groupId>com.android.support</groupId>
  <artifactId>design-button</artifactId>
  <versioning>
    <release>28.0.0-alpha1</release>
    <versions>
      <version>28.0.0-alpha1</version>
    </versions>
    <lastUpdated>20180223211956</lastUpdated>
  </versioning>
</metadata>