pub fn from_connector_with_config(connector: C, config: HttpConfig) -> Self {
        let mut builder = HyperClient::builder();
        config
            .read_buf_size
            .map(|sz| builder.http1_read_buf_exact_size(sz));
        config
            .pool_idle_timeout
            .map(|t| builder.pool_idle_timeout(t));
        let inner = builder.build(connector);

        HttpClient {
            inner,
            local_agent_prepend: None,
            local_agent_append: None,
        }
    }
Allows for a custom connector to be used with the HttpClient
with extra configuration options
rusoto/core/src/request.rs