I cannot change the encription keys to sign and decript SAML messages

I’ve followed all guides and read the API documentation.

https://auth0.com/docs/authenticate/protocols/saml/saml-sso-integrations/sign-and-encrypt-saml-requests
https://auth0.com/docs/api/management/v2#!/Connections/patch_connections_by_id

I cannot make the API work to patch my SAML connection with the correct keys. Everytime I get “The signing certificate public key is required”. This is nowhere to be found in the documentation.