public ChatClient getClient(final String key) {
        return CHAT_CLIENT_MAP.get(key);
    }
Gets chatClient.

@param key key
@return the instance
shenyu-plugin/shenyu-plugin-ai/shenyu-plugin-ai-request-transformer/src/main/java/org/apache/shenyu/plugin/ai/transformer/request/cache/ChatClientCache.java