Is there a good example of how to implement oauth2 authentication using the cdk?

you can use

Oauth2Authenticator

:

from airbyte_cdk.sources.streams.http.requests_native_auth import Oauth2Authenticator

example from hubspot https://github.com/airbytehq/airbyte/blob/master/airbyte-integrations/connectors/source-hubspot/source_hubspot/streams.py#L124