[9.0] Add package-info.java and javadocs to document Entitlements design and implementation (#127023)#127141

elasticsearchmachine merged 1 commit intoelastic:9.0elastic/elasticsearch:9.0from

ldematte:backport/9.0/entitlements/package-docsldematte/elasticsearch:backport/9.0/entitlements/package-docsCopy head branch name to clipboard