Answer
Already-included 3rd-party jars shipped with IFS Cloud can be found in Build Home under source\fndbas\server\lib and source\fndbas\framework\thirdparty — that's where to look to see what's already available before assuming you need to add something new. For adding your own new 3rd-party jar so it's correctly included by the automated build process (not just working locally in Developer Studio), place it under source\fndbas\projection\lib\ instead of the framework\thirdparty directory — the thirdparty directory works for local development but isn't picked up the same way by the automated topic-environment build pipeline.