spring-ai/langchain4j-interop/src/broken/OldChatService.java

import java.util.List;

import org.springframework.ai.chat.client.ChatClient;
import reactor.core.publisher.Flux;

// The original ChatService, unchanged: this one is expected to still compile.
class OldChatService {
    private final ChatClient chatClient;

    OldChatService(ChatClient.Builder builder) {
        this.chatClient = builder
            .defaultSystem("You are a senior Java architect. Be precise and concise.")
            .build();
    }

    public String ask(String userMessage) {
        return chatClient.prompt().user(userMessage).call().content();
    }

    public Flux<String> stream(String userMessage) {
        return chatClient.prompt().user(userMessage).stream().content();
    }

    public ArchitectureReview reviewCode(String codeSnippet) {
        return chatClient.prompt()
            .user(u -> u.text("Review this Java code for production readiness: {code}").param("code", codeSnippet))
            .call()
            .entity(ArchitectureReview.class);
    }

    public record ArchitectureReview(String verdict, List<String> issues, List<String> suggestions, int score) { }
}