code: public static void toArmeria(io.netty.handler.codec.http.HttpHeaders inHeaders, HttpHeaders out) {
          final Iterator<Entry<CharSequence, CharSequence>> iter = inHeaders.iteratorCharSequence();
          // Choose 8 as a default size because it is unlikely we will see more than 4 Connection headers values,
          // but still allowing for "enough" space in the map to reduce the chance of hash code collision.
          final CharSequenceMap connectionBlacklist =
                  toLowercaseMap(inHeaders.valueCharSequenceIterator(HttpHeaderNames.CONNECTION), 8);
          StringJoiner cookieJoiner = null;
          while (iter.hasNext()) {
              final Entry<CharSequence, CharSequence> entry = iter.next();
              final AsciiString aName = HttpHeaderNames.of(entry.getKey()).toLowerCase();
              if (HTTP_TO_HTTP2_HEADER_BLACKLIST.contains(aName) || connectionBlacklist.contains(aName)) {
                  continue;
              }
  
              // https://tools.ietf.org/html/rfc7540#section-8.1.2.2 makes a special exception for TE
              if (aName.equals(HttpHeaderNames.TE)) {
                  toHttp2HeadersFilterTE(entry, out);
                  continue;
              }
  
              // Cookies must be concatenated into a single octet string.
              // https://tools.ietf.org/html/rfc7540#section-8.1.2.5
              final CharSequence value = entry.getValue();
              if (aName.equals(HttpHeaderNames.COOKIE)) {
                  if (cookieJoiner == null) {
                      cookieJoiner = new StringJoiner(COOKIE_SEPARATOR);
                  }
                  COOKIE_SPLITTER.split(value).forEach(cookieJoiner::add);
              } else {
                  out.add(aName, convertHeaderValue(aName, value));
              }
          }
  
          if (cookieJoiner != null && cookieJoiner.length() != 0) {
              out.add(HttpHeaderNames.COOKIE, cookieJoiner.toString());
          }
      }
docs: Converts the specified Netty HTTP/1 headers into Armeria HTTP/2 headers.