code: public static String getArtworkUrl(SoundCloudTrack track, String size) {
          String defaultUrl = track.getArtworkUrl();
          if (defaultUrl == null) {
              return null;
          }
          switch (size) {
              case MINI:
              case TINY:
              case SMALL:
              case BADGE:
              case LARGE:
              case XLARGE:
              case XXLARGE:
              case XXXLARGE:
                  return defaultUrl.replace(LARGE, size);
              default:
                  return defaultUrl;
          }
      }
docs: Retrieve the artwork url of a track pointing to the requested size.
  <p/>
  By default, {@link fr.tvbarthel.cheerleader.library.client.SoundCloudTrack#getArtworkUrl()}
  points to the {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#LARGE}
  <p/>
  Available size are :
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#MINI}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#TINY}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#SMALL}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#BADGE}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#LARGE}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#XLARGE}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#XXLARGE}
  {@link fr.tvbarthel.cheerleader.library.helpers.SoundCloudArtworkHelper#XXXLARGE}
  
  @param track track from which artwork url should be returned.
  @param size  wished size.
  @return artwork url or null if no artwork are available.