Clojurians Log v2

I am trying to use java interop with langchain4j, more specificaly the Aiservices. My problem is that it requires an interface with one method for the Aiservices builder. So i have the following clojure protocol implemented:

(defprotocol Assistant
  (^String answer [this ^String query]))

Not sure if the hint do anything here, it seems not, i use it with Aiservices in the following way:

(defn make-assistant [model retriever]
 (try
  (.build (doto
            (AiServices/builder rag_base.core.Assistant)
            (.chatLanguageModel model)
            (.contentRetriever retriever)))
  (catch Throwable t (.println System/out t))))

Where rag-base.core is the namespace, hence rag_base.core.Assistant is the java interface of the corresponding protocol. However when i call make-assistant the type of the class i get is jdk.proxy4.$Proxy46 and wean a call the answear method i get

; eval (current-form): (answer assistant "test")
; (err) Execution error (IllegalConfigurationException) at dev.langchain4j.exception.IllegalConfigurationException/illegalConfiguration (IllegalConfigurationException.java:12).
; (err) Illegal method return type: class java.lang.Object

Indicating that is something wrong with the return type, so type hints dont work what can i do here ?