Hello there, I have list of case on which I'm getting my case query result, now based on condition that - OldValue not null condition I want to get those records into new List.
Basically my aim is to filter out those record which has OldValue, newValue (which is coming from Histories field tracking )
 

public static void SessionHistory(){
        try {

            Map<id,list<case>> UserEvent = new Map<id,list<case>>();
            List<case> tempCaseList = null;
            List<case> newEvents1 = new List<case>();

           List<case> newEvents = [SELECT OwnerId,(SELECT OldValue, id, NewValue, CreatedById, CreatedBy.Name, caseId,  case.Ownerid, case.DOS__c FROM Histories where field='status'), Account.Name, Patient_Customer__r.dob__c, CaseNumber,Status,Appointment_Start_Time__c,Appointment_End_Time__c, 
            DOS__c,FacilitiesV3__c,Place_of_Service__c,Practice_Procedure_Code__c,Practice_Procedure_Code__r.Type_of_Service__c,
            Insurance__c,Duration__c, Actual_Duration__c, Unit__c, Actual_Unit__c, Practice_Procedure_Code__r.name, Billed_Amount__c,
            Id,Authorizations__c,Facility_Type__c, Patient_Customer__c, PA_NO_PA__c,Provider__c, Client_Insurance__c,Authorization_Number__c,
            Client_Name__c, Provider_Name__c, Location_Name__c,Insurance_Name__c, Sup_Provider__r.Name FROM Case WHERE Recordtype.Name ='Session'
             ORDER BY OwnerId limit 1800];


             if(newEvents.contains(OldValue)){
               newEvents1.addAll(newEvents);
             }

             system.debug('new history'+ newEvents1);

I tried with listname.contains('OldValue') but it's not working. Please if someone can suggest right approach. It will be very helpful.