Spring-ai Change return type of getMedia in MediaContent to List<Media>

from

public interface MediaContent extends Content {

    /**
     * Get the media associated with the content.
     */
    Collection<Media> getMedia();

}

to

``` public interface MediaContent extends Content {

/**
 * Get the media associated with the content.
 */
List<Media> getMedia();

}

Comment From: markpollack

done in dfbc394f8311b4c919079a734280aa56f6e1b7d0