The AbstractCase rule class acts as the interface between the fixed decision details processing provided by the Engine, and the product-specific rules for the calculation of decision details for a case (to provide details for a top-level display category screen; the interface for sub-screens is described below).
Unlike the interface rule classes for eligibility/entitlement and key decision factors, the ProductDecisionDetailsRuleSet.AbstractCase interface rule class does not mandate a fixed data structure for concrete sub-rule-classes to implement. Later we will see how the Engine "walks" free-form data to calculate decision details for the case.