private static BiPredicate<? super RequestContext, ? super HttpHeaders> previewerPredicate(
            MediaTypeSet mediaTypeSet) {
        requireNonNull(mediaTypeSet, "mediaTypesSet");
        return (ctx, headers) -> {
            final MediaType contentType = headers.contentType();
            if (contentType == null) {
                return false;
            }
            return mediaTypeSet.match(contentType) != null;
        };
    }
Returns a newly-created {@link ContentPreviewerFactory} based on the properties of this builder.
core/src/main/java/com/linecorp/armeria/common/logging/ContentPreviewerFactoryBuilder.java