Salesforce Apex Class EmailAction has an @InvocableMethod for sending emails from Process Builder

EmailAction.cls

global class EmailAction {
    
    @InvocableMethod(label='Send Email')
    global static List<EmailActionResult> sendEmails(List<EmailActionRequest> requests) {
        
        List<EmailActionResult> results = new List<EmailActionResult>();
        
        for(EmailActionRequest request : requests){
            results.add(sendEmail(request));
        }
        
        return results;
    }
    
    public static EmailActionResult sendEmail(EmailActionRequest request) {
        
        Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();
                
        if (String.isNotBlank(request.subject)){
            mail.setSubject(request.subject);   
        }
        
        if (request.getBccAddresses().size() > 0){
            mail.setBccAddresses(request.getBccAddresses()); 
        }
        
        if (request.getCcAddresses().size() > 0){
            mail.setBccAddresses(request.getCcAddresses()); 
        }
        
        if (String.isNotBlank(request.emailTemplateId)){
            mail.setTemplateId(request.emailTemplateId);
        }
        
        if (String.isNotBlank(request.htmlBody)){
            mail.setHtmlBody(request.htmlBody);
        }
        
        if (String.isNotBlank(request.plainTextBody)){
            mail.setPlainTextBody(request.plainTextBody);
        }
        
        if (String.isNotBlank(request.orgWideEmailAddressId)){
            mail.setOrgWideEmailAddressId(request.orgWideEmailAddressId);
        }
        
        if (String.isNotBlank(request.displayName)){
            mail.setSenderDisplayName(request.displayName);
        }
        
        if (String.isNotBlank(request.targetObjectId)){
            // Only User, Contact, Lead, or Person objects are allowed for targetObjectId
            mail.setTargetObjectId(request.targetObjectId); 
        }
        
        if (String.isNotBlank(request.whatId)){
            mail.setWhatId(request.whatId);
        }
        
        mail.setSaveAsActivity(request.saveAsActivity);
        mail.setOptOutPolicy('FILTER');
        
        Messaging.SingleEmailMessage[] messages = new List<Messaging.SingleEmailMessage>();
        messages.add(mail);
        
        Messaging.SendEmailResult[] results = Messaging.sendEmail(messages);
        
        EmailActionResult emailActionResult = new EmailActionResult();
        
        for(Messaging.SendEmailResult result :results) {                
            
            if(result.IsSuccess()) {
                
                emailActionResult.isSuccess = true;
                
            } else {
                
                emailActionResult.isSuccess = false;
                Messaging.SendEmailError[] errors = result.getErrors(); 
                
                if (errors.size() > 0 ){
                    
                    emailActionResult.errorMessage = errors[0].getMessage();
                    System.debug('EmailAction error: ' + errors[0].getMessage()); 
                    
                }
            }
        } 
        
        return emailActionResult;
    }
    
    global class EmailActionResult {
        
        @InvocableVariable
	    global Boolean isSuccess;
        
        @InvocableVariable
	    global String errorMessage;
    }
    
    global class EmailActionRequest {
        
        private List<String> bccAddresses;
        
        private List<String> ccAddresses;
        
        @InvocableVariable(required=false)
        global Id emailTemplateId;
        
        @InvocableVariable(required=false)
        global String subject;
        
        @InvocableVariable(required=false)
        global String htmlBody;
        
        @InvocableVariable(required=false)
        global String plainTextBody;
        
        @InvocableVariable(required=false)
        global String ccAddress;
        
        @InvocableVariable(required=false)
        global String bccAddress;
        
        @InvocableVariable(required=false)
        global Id orgWideEmailAddressId;
        
        @InvocableVariable(required=false)
        global String displayName;
        
        @InvocableVariable(required=true)
        global Id targetObjectId;
        
        @InvocableVariable(required=true)
        global Id whatId;
        
        @InvocableVariable(required=false)
        global Boolean saveAsActivity = true;
        
        public EmailActionRequest() {
            ccAddresses = new List<String>();
            bccAddresses = new List<String>();
        }
        
        public List<String> getCcAddresses(){
            
            if (ccAddresses != null){
                ccAddresses.add(ccAddress);    
            }
            
            return ccAddresses;
        }
        
        public List<String> getBccAddresses(){
            
            if (bccAddress != null){
                bccAddresses.add(bccAddress);    
            }
            
            return bccAddresses;
        }
    }
}

EmailActionTests.cls

@isTest
public class EmailActionTests {

    @isTest
    static void sendEmails_Success(){
        
        // arrange
        Contact target = new Contact();
        target.FirstName = 'Dee';
        target.LastName = 'Licious';
        target.email = 'dee@example.com';
        
        insert target;
        
        Account what = new Account();
        what.Name = 'Ghostbusters';
        
        insert what;
        
        EmailAction.EmailActionRequest request = new EmailAction.EmailActionRequest();
        request.bccAddress = 'bcc@example.com';
        request.ccAddress = 'cc@example.com';
        request.displayName = 'Acme Inc';
        request.saveAsActivity = true;
        request.subject = 'Test Subject';
        request.targetObjectId = target.Id;
        request.whatId = what.Id;
        request.plainTextBody = 'Hello World';
        request.htmlBody = '<b>Hello World</b>';
        
        List<EmailAction.EmailActionRequest> requests = new List<EmailAction.EmailActionRequest>();
        requests.add(request);
        
        // act
        List<EmailAction.EmailActionResult> results = EmailAction.sendEmails(requests);
        
        // assert
        System.assertEquals(1, results.size());
        System.assertEquals(true, results[0].isSuccess);
    }
}