authenticateProxy property Null safety

void authenticateProxy=(Future<bool> f(String host, int port, String scheme, String realm)?)

Sets the function to be called when a proxy is requesting authentication. Information on the proxy in use and the security realm for the authentication are passed in the arguments host, port and realm.

The function returns a Future which should complete when the authentication has been resolved. If credentials cannot be provided the Future should complete with false. If credentials are available the function should add these using addProxyCredentials before completing the Future with the value true.

If the Future completes with true the request will be retried using the updated credentials. Otherwise response processing will continue normally.

Implementation

void set authenticateProxy(
    Future<bool> f(String host, int port, String scheme, String realm)?);