Within the context of WSO2 outbound SCIM provisioning, suppose that the participating external IDP was shutdown for several hours and missed WSO2's outbound provisioning messages. In this scenario, does WSO2 provide a way for the external IDP to request another push provisioning message to re-sync with WSO2's user store?
SCIM is client oriented. There is no way into your WSO2 instance to initiate a Pull request through SCIM from the external IdP.
It must come from the external IdP to initiate a global push from its side after the reboot/reconnection.