New sets up a new GenMap based on the supplied configuration.

ErrGenMapClosed is returned by blocking operations called on a GenMap that has been closed.

ErrNoGenerator is the only possible error returned by New and indicates that the required generator config value was not supplied.

Config configures a generative map.

GenMap is a mapping used to pre-generate and store values that we want to always have available *immediately*, such as client tls configs.