Set the default HTTP protocol version. The value is "HTTP/2.0" or "HTTP/1.1". If the value is null,
the server or client will negotiate a HTTP protocol version using ALPN.
@param protocol the default HTTP protocol version. The value is "HTTP/2.0" or "HTTP/1.1".
Set the default HTTP protocol version. The value is "HTTP/2.0" or "HTTP/1.1". If the value is null, the server or client will negotiate a HTTP protocol version using ALPN.
@param protocol the default HTTP protocol version. The value is "HTTP/2.0" or "HTTP/1.1".