netty4-http component is setting an invalid "host" HTTP header

The netty4-http component is setting an invalid "host" HTTP header when no port is defined in the uri for requests.

netty4-http sets the header in DefaultNettyHttpBinding.toNettyRequest where URI is used to parse the uri string but URI give -1 if no port is defined. For example the host header could be set to "hostname:-1" which is not accepted of some proxy servers that check the validity of the host header. For example Apache proxy will return a http error 400(Bad request).

See https://tools.ietf.org/html/rfc7230#section-5.4

// This is how it's done in DefaultNettyHttpBinding.toNettyRequest
URI u = new URI(uri);
String hostHeader = u.getHost() + (u.getPort() == 80 ? "" : ":" + u.getPort());
request.headers().set(HttpHeaderNames.HOST.toString(), hostHeader);
LOG.trace("Host: {}", hostHeader);

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One solution could be:

URI u = new URI(uri);
int port = u.getPort();
String hostHeader = u.getHost() + (port == 80 || port ==-1 ? "" : ":" + port);
request.headers().set(HttpHeaderNames.HOST.toString(), hostHeader);