Kudos to the team for releasing the amazing and long-awaited feature 👏

I would like to emphasize the importance of supporting Java arrays. This might become an issue when integrating CEL into software having a mature and stable data model. For example, JSON Web Token, a structure central to OAuth and OpenID Connect, is modeled in Keycloak as a Jackson-annotated value class. The audience parameter, which supports multiple values, is modeled as String[]. When trying to register the JsonWebToken with CEL, I'm getting the following error:

ERROR: Unsupported type for property 'audience' in class org.keycloak.representations.JsonWebToken
ERROR: Unsupported Java type for CEL mapping: [Ljava.lang.String;

As a workaround, I can parse the string representation of the JWT into a Protobuf Value, which is redundant and adds extra overhead. Also, I doubt we can convince Keycloak to change the type to List as it would be a huge breaking change to Keycloak and existing extensions. That said, it would be very nice to have a native support for Java arrays other than byte[] (for Keycloak, String[] in the first place).