Hello world~

I am very new to Apex. I am currently working on the code below that would allow a lead to be removed from a cadence when deemed fit:

public class RemoveTargetFromSalesCadence {

   @InvocableMethod(label='Remove Target From Sales Cadence' description='Uses REST Invocable Action to remove a Target to a Sales Cadence')
   public static void removeTarget(List<RemoveTargetRequest> targetsToRemove) {
       System.debug('*** Targets to remove *** ' + targetsToRemove);
       if (targetsToRemove != null) {
           for (RemoveTargetRequest req : targetsToRemove) {
               System.debug('*** request *** ' + req);
               System.debug('\ttarget: ' + req.targetId);
               System.debug('\tcompletion reason code: ' + req.completionReasonCode);
               sendRequest(req.targetId, req.completionReasonCode);
           }
       } else {
           System.debug('*** null targetsToRemove received ***');
       }
   }

   @future(callout = true)
   private static void sendRequest(String targetId, String completionReasonCode) {
       String sfdcURL = URL.getSalesforceBaseUrl().toExternalForm();
       String actionsRestURL = sfdcURL + '/services/data/v45.0/actions';
       String removeTargetRESTUrl = actionsRestURL + '/standard/removeTargetFromSalesCadence';

       HttpRequest httpReq = new HttpRequest();
       httpReq.setMethod('POST');
       httpReq.setHeader('Authorization', 'OAuth ' + UserInfo.getSessionId());
       httpReq.setHeader('Authorization', 'Bearer ' + UserInfo.getSessionId());
       httpReq.setEndpoint(removeTargetRESTUrl);
       httpReq.setHeader('Content-Type', 'application/json');
       httpReq.setBody('{"inputs" : [{"completionReasonCode" : "' + completionReasonCode + '", "targetId" : "' + targetId + '"}]}');

       String response = '';
       try {
           Http http = new Http();
           HttpResponse httpResponse = http.send(httpReq);
           if (httpResponse.getStatusCode() == 200) {
               response = JSON.serializePretty(JSON.deserializeUntyped(httpResponse.getBody()));
           } else {
               System.debug('http response: ' + httpResponse.getBody());
               throw new CalloutException(httpResponse.getBody());
           }
       } catch (System.Exception e) {
           System.debug('ERROR! ' + e);
           throw e;
       }

       System.debug('response: ' + response);
   }

   public class RemoveTargetRequest {
       @InvocableVariable(required=true)
       public Id targetId;

       @InvocableVariable(required=true)
       public String completionReasonCode;
   }
}

I am getting this error message after deploying it to my production and I don't know what this means. Could somebody please clarify and help me out? 


Thanks so much.