Help with setting Email TO address in customized Email Publisher Quick Action

Question

I have a running implementation of a customized Email Publisher in the Case Feed, which implement QuickActionDefaultHandler to pre-populate Email Templates based on my Cases Record Type. Below is the Apex Class:

global class EmailPublisherLoader implements QuickAction.QuickActionDefaultsHandler {
// Empty constructor
    global EmailPublisherLoader() { }

// The main interface method
    global void onInitDefaults(QuickAction.QuickActionDefaults[] defaults) {
        QuickAction.SendEmailQuickActionDefaults sendEmailDefaults = null;

        // Check if the quick action is the standard Case Feed send email action
        for (Integer j = 0; j < defaults.size(); j++) {
            if (defaults.get(j) instanceof QuickAction.SendEmailQuickActionDefaults && 
               defaults.get(j).getTargetSObject().getSObjectType() == 
                   EmailMessage.sObjectType && 
               defaults.get(j).getActionName().equals('Case.Email') && 
               defaults.get(j).getActionType().equals('Email')) {
                   sendEmailDefaults = 
                       (QuickAction.SendEmailQuickActionDefaults)defaults.get(j);
                   break;
            }
        }

         if (sendEmailDefaults != null) {
            Case c = [SELECT Status, contact.Email, Additional_To__c, Additional_CC__c, Additional_BCC__c, RecordType.name FROM Case WHERE Id=:sendEmailDefaults.getContextId()];
            EmailMessage emailMessage = (EmailMessage)sendEmailDefaults.getTargetSObject();  
    //set TO address
         if (c.contact.Email == c.Additional_To__c){
            emailMessage.toAddress = (c.contact.Email);
            }
            else{
            if (c.Additional_To__c != null){
            emailMessage.toAddress = (c.contact.Email+' '+c.Additional_To__c);
            }
            }

In addition, I am setting the TO address according a combination of the Case Contact and the custom field - 'Additional_To__c'. The above solution is setting the TO properly, but when the Case Contact does exist in the 'Additional_To__c' as follows:

The outcome is a duplicity of the Case Contact - '[email protected]':

Answer 1

I was able to resolve this by using 'indexOf' for String 'includes' condition as follows:

 //set TO address
     String contactEmail = c.contact.Email; 
     if (c.contact.Email == c.Additional_To__c){
        emailMessage.toAddress = (c.contact.Email);
        }
        else{
            if (c.Additional_To__c != null){
                //contactEmail is included in Additional TO
                if (c.Additional_To__c.indexOf(contactEmail) != -1){
                    emailMessage.toAddress = (c.Additional_To__c);
                    }
            else{
                emailMessage.toAddress = (c.contact.Email+' '+c.Additional_To__c);
                }
            }
        }