loadMessages() protected method
Loads the message translation for the specified $language and $category. If translation for specific locale code such as en-US isn't found it tries more generic en. When both are present, the en-US messages will be merged over en. See loadFallbackMessages() for details. If the $language is less specific than $sourceLanguage, the method will try to load the messages for $sourceLanguage. For example: $sourceLanguage is en-GB, $language is en. The method will lo