D365 F&O

// Custom Extension for High-Volume Integrations
[ExtensionOf(classStr(SalesOrderContract))]
final class D365S_SalesContract_Extension
{
    public void parmExternalRefId(str _value)
    {
        // Validating external data during OData handshake
        if (!this.validateReference(_value))
        {
            throw error("Integration validation failed.");
        }
        next parmExternalRefId(_value);
    }
}