Constructs a new AWS access control policy condition that allows an
access control statement to restrict subscriptions to an Amazon SNS topic
based on the protocol being used for the subscription. For example, this
condition can restrict subscriptions to a topic to endpoints using HTTPS
to ensure that messages are securely delivered.

- protocol (String)
- The protocol against which to compare the requested protocol for an Amazon SNS topic subscription.

A new access control policy condition that compares the
notification protocol requested in a request to subscribe to an
Amazon SNS topic with the protocol value specified.