fn discover_common_core_api_version(
client_versions: &SupportedCoreApiVersions,
peer_versions: &BTreeMap<PeerId, SupportedCoreApiVersions>,
) -> Option<ApiVersion>
fn discover_common_core_api_version(
client_versions: &SupportedCoreApiVersions,
peer_versions: &BTreeMap<PeerId, SupportedCoreApiVersions>,
) -> Option<ApiVersion>