core/play/src/main/java/play/i18n/MessagesImpl.java
public String at(String key, Object... args) {
    return messagesApi.get(lang, key, args);
  }
public String at(String key, Object... args) {
    return messagesApi.get(lang, key, args);
  }
Get the message at the given key.

<p>Uses `java.text.MessageFormat` internally to format the message.

@param key the message key
@param args the message arguments
@return the formatted message or a default rendering if the key wasn't defined