Inserting JavaDoc for list size helperfunction

src/main/java/CredentialRepository.java

@@ -128,6 +128,11 @@ public class CredentialRepository implements CredentialRepositoryInterface{
 
     }
 
+    /**
+     * helper function to check list size after insertion / deletion
+     * @return
+     */
+
     private int getListSize()
     {
         return this.credentials.size();