Validate all TE header instances for HTTP/2 request conformance.

[arturobernalg]

Reject any TE value other than trailers (including additional TE headers).

[ok2c]

@arturobernalg I would rewrite it as

    @Override
    public void process(final HttpRequest request, final EntityDetails entity, final HttpContext localContext)
            throws HttpException, IOException {
        Args.notNull(request, "HTTP request");
        for (int i = 0; i < illegalHeaderNames.length; i++) {
            final String headerName = illegalHeaderNames[i];
            if (request.containsHeader(headerName)) {
                if (HttpHeaders.TE.equalsIgnoreCase(headerName)) {
                    validateTE(request);
                } else {
                    throw new ProtocolException("Header '%s' is illegal for HTTP/2 messages", headerName);
                }
            }
        }
    }

    private static void validateTE(final HttpRequest request) throws ProtocolException {
        boolean sawAnyToken = false;
        boolean sawInvalidToken = false;
        for (final Iterator<String> it = MessageSupport.iterateTokens(request, HttpHeaders.TE); it.hasNext(); ) {
            final String token = it.next();
            sawAnyToken = true;
            if (!"trailers".equalsIgnoreCase(token)) {
                sawInvalidToken = true;
                break;
            }
        }
        if (sawInvalidToken || !sawAnyToken) {
            throw new ProtocolException("Header '%s' is illegal for HTTP/2 messages", HttpHeaders.TE);
        }
    }

[arturobernalg]

@arturobernalg I would rewrite it as

    @Override
    public void process(final HttpRequest request, final EntityDetails entity, final HttpContext localContext)
            throws HttpException, IOException {
        Args.notNull(request, "HTTP request");
        for (int i = 0; i < illegalHeaderNames.length; i++) {
            final String headerName = illegalHeaderNames[i];
            if (request.containsHeader(headerName)) {
                if (HttpHeaders.TE.equalsIgnoreCase(headerName)) {
                    validateTE(request);
                } else {
                    throw new ProtocolException("Header '%s' is illegal for HTTP/2 messages", headerName);
                }
            }
        }
    }

    private static void validateTE(final HttpRequest request) throws ProtocolException {
        boolean sawAnyToken = false;
        boolean sawInvalidToken = false;
        for (final Iterator<String> it = MessageSupport.iterateTokens(request, HttpHeaders.TE); it.hasNext(); ) {
            final String token = it.next();
            sawAnyToken = true;
            if (!"trailers".equalsIgnoreCase(token)) {
                sawInvalidToken = true;
                break;
            }
        }
        if (sawInvalidToken || !sawAnyToken) {
            throw new ProtocolException("Header '%s' is illegal for HTTP/2 messages", HttpHeaders.TE);
        }
    }

@ok2c All right. I made the change