I have a list with multiple elements associated with one name. I want to check only if the email address in the first element is empty - the others I don't care if they are blank. Here is my list:

public List<Opportunity> opportunity {
        get {
            return [SELECT Name, Ashoka_Website_Profile_Link__c,
            (SELECT Engagement_Role__c.Name,
                Engagement_Role__c.Contact__r.Email, 
                Engagement_Role__c.Contact__r.Name,
                Engagement_Role__c.Contact__r.Account.Name,
                Engagement_Role__c.Contact__r.Id
            FROM Opportunity.R00NR0000000UWbWMAW WHERE Role__c='Nominator' AND Engagement_Role__c.Contact__r.Email != NULL ) 
            FROM Opportunity WHERE Id = :oppId];
            }
    }

Originally, I did not use a list but instead just created a new Opportunity object. My code all ran fine. I used this if-statement and for-loop after (pardon the terrible naming, it was not my doing):

        if (opportunity.R00NR0000000UWbWMAW[0].Contact__r.Email != null) {
            addresses = opportunity.R00NR0000000UWbWMAW[0].Contact__r.Email;
            
            for (Integer i = 1; i < opportunity.R00NR0000000UWbWMAW__r.size(); i++) {
                if (opportunity.R00NR0000000UWbWMAW[i].Contact__r.Email != null) {          
                    addresses += ':' + opportunity.R00NR0000000UWbWMAW[i].Contact__r.Email;
                }
            }
        }

But since replacing my code with the list, my code doesn't work anymore. How then would the syntax look? I suppose first I would need to check if the list is empty in the first place, but after that, how would I check if the email field specifically is empty?