static BodyPart of(HttpHeaders headers, HttpData content) {
        requireNonNull(content, "content");
        return of(headers, StreamMessage.of(content));
    }
Returns a new {@link BodyPart} using the specified {@link HttpHeaders} and
{@code bytes}.
core/src/main/java/com/linecorp/armeria/common/multipart/BodyPart.java