public DnsAddressEndpointGroupBuilder port(int port) {
        checkArgument(port > 0 && port <= 65535, "port: %s (expected: 1...65535)", port);
        this.port = port;
        return this;
    }
Sets the port number of the {@link Endpoint}s created by {@link DnsAddressEndpointGroup}.
By default, the port number of the {@link Endpoint}s will remain unspecified and the protocol-dependent
default port number will be chosen automatically, e.g. 80 or 443.
core/src/main/java/com/linecorp/armeria/client/endpoint/dns/DnsAddressEndpointGroupBuilder.java