private static String joinHeaders(Set<AsciiString> headers) {
        return HEADER_JOINER.join(headers);
    }
Joins the given set of headers into a single string.
This can be useful for creating a comma-separated list of headers.

@param headers The set of headers to be joined.
@return A {@link String} representing the joined headers.
core/src/main/java/com/linecorp/armeria/internal/server/CorsHeaderUtil.java