@Override public Jsonable get() { List<String> allThumbnailTypes = ThumbnailUtil.getThumbnailMimeTypes(); // Tiff images aren't displayable in most web browsers, so let's remove them from here. List<String> supportedThumbnailTypes = newArrayList(allThumbnailTypes); supportedThumbnailTypes.remove("image/x-tiff"); supportedThumbnailTypes.remove("image/tiff"); return new JsonableString(Joiner.on(",").join(supportedThumbnailTypes)); } }