@Override
        public HttpFile build() {
            return new HttpDataFile(content, clock(), lastModifiedMillis,
                                    isDateEnabled(), isLastModifiedEnabled(),
                                    entityTagFunction(), buildHeaders());
        }
Returns a newly created {@link HttpFile} with the properties configured so far. If this builder was
created with {@link HttpFile#builder(HttpData)} or {@link HttpFile#builder(HttpData, long)},
the returned instance will always be an {@link AggregatedHttpFile}.
core/src/main/java/com/linecorp/armeria/server/file/HttpFileBuilder.java