How to Constraint Next Button In Oracle CPQ Configuration

Requirement: Business want to constraint Next button as Model have multi step model. The next button will be visible but if the attributes in the first configuration flow is is not fully selected and next button is clicked, system should populate an error.

Possible Solution: We have single select picklist in first config flow. We used pick maps at the end of config flow attribute. Then the pick map is applied to a text attribute. This text attribute have a constraint rule which constraint all the single select pick list if its value is blank. However, this is hiding the Next button, which is not a intended requirement.