Bulk State Transition

Reading Only

You are given two Maps of Opportunities. oldMap representing the Opportunities before update. newMap representing the Opportunities after update.

Each map has the Opportunity Id as the key, and the Opportunity object as the value. The maps will never be null or empty.

Implement the method called getOppsWithStageChange(...) that returns a Set of Opportunity Ids where the StageName has changed between the old and new versions. You can assume this code is called from a Trigger Context and the maps represent Trigger.oldMap and Trigger.newMap

Example:

Input

oldMap = {  
            '006aj00000Bt9ngAAB' => Opportunity(Id='006aj00000Bt9ngAAB', StageName='Prospecting'),  
            '006aj00000Bt8oXAAD' => Opportunity(Id='006aj00000Bt8oXAAD', StageName='Closed Won'),  
            '006aj00000Bt4loABC' => Opportunity(Id='006aj00000Bt4loABC', StageName='Prospecting')
        }

newMap = {  
            '006aj00000Bt9ngAAB' => Opportunity(Id='006aj00000Bt9ngAAB', StageName='Value Proposition'),  
            '006aj00000Bt8oXAAD' => Opportunity(Id='006aj00000Bt8oXAAD', StageName='Closed Won'),  
            '006aj00000Bt4loABC' => Opportunity(Id='006aj00000Bt4loABC', StageName='Closed Lost')
        }

Output: A Set of Ids containing 006aj00000Bt9ngAAB and 006aj00000Bt4loABC

Constraints You should not modify the input maps. Trigger.old, Trigger.oldMap, Trigger.new, Trigger.newMap are not available in this context.