refactored member assignment for new tasks

Signed-off-by: Stephan Richter <s.richter@srsoftware.de>

core/src/main/java/de/srsoftware/umbrella/core/model/User.java

@@ -13,8 +13,9 @@ import de.srsoftware.umbrella.core.exceptions.UmbrellaException;
 import org.json.JSONObject;
 
 public class User {
-	private String lang, name;
-	private EmailAddress email;
+	private final String lang;
+    private final String name;
+	private final EmailAddress email;
 
 	public User(String name, EmailAddress email, String languageCode){
 		lang = languageCode;
@@ -51,6 +52,6 @@ public class User {
 
 	@Override
 	public String toString() {
-		return format("{0} ({1})",name,email);
+		return email == null ? name : format("{0} ({1})",name,email);
 	}
 }