In complex web-facing software, interfaces are very commonly used to model different kinds of context objects (examples from Keycloak: OAuth2GrantType.Context, TokenExchangeContext). These objects would perfectly complement any CEL policy being part of request processing. Unfortunately, adding such an object as a variable won't work with Native Extensions, because only List and Map subinterfaces are currently supported.

Would be really nice for CEL to support Java interfaces in a native manner.