@VisibleForTesting
    static BiFunction<? super HttpHeaders, ? super ByteBuf, String> hexDumpProducer() {
        return (headers, byteBuf) -> ByteBufUtil.hexDump(byteBuf);
    }
Returns a newly-created {@link ContentPreviewerFactory} based on the properties of this builder.
core/src/main/java/com/linecorp/armeria/common/logging/ContentPreviewerFactoryBuilder.java