Extend or custom RetryStrategy?

[cprieto]

Is there a way we can extend or customize the retry strategy? We have a case scenario (depending on customer) we want for certain verbs or operations to return longer retries (a good example, throttling for head) so just using RetryConfig or a RetryClassifier is not enough.
I had checked the source code, but I can't see a way to override it while creating a client builder for S3 so I guess is not a possibility? I could be wrong but I want to confirm.