diff -r 2a90d105edec -r dd0a45ae25d7 src/main/java/de/uapcore/lightpit/entities/User.java
--- a/src/main/java/de/uapcore/lightpit/entities/User.java	Sat May 16 11:37:57 2020 +0200
+++ b/src/main/java/de/uapcore/lightpit/entities/User.java	Sat May 16 13:29:44 2020 +0200
@@ -34,18 +34,18 @@
 
     public static final int ANONYMOUS_USERID = -1;
 
-    private final int userID;
+    private final int id;
     private String username;
     private String mail;
     private String givenname;
     private String lastname;
 
-    public User(int userID) {
-        this.userID = userID;
+    public User(int id) {
+        this.id = id;
     }
 
-    public int getUserID() {
-        return userID;
+    public int getId() {
+        return id;
     }
 
     public String getUsername() {
@@ -82,9 +82,11 @@
 
     public String getDisplayname() {
         StringBuilder dn = new StringBuilder();
-        dn.append(givenname);
+        if (givenname != null)
+            dn.append(givenname);
         dn.append(' ');
-        dn.append(lastname);
+        if (lastname != null)
+            dn.append(lastname);
         dn.append(' ');
         if (mail != null && !mail.isBlank()) {
             dn.append("<"+mail+">");
@@ -98,11 +100,11 @@
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         User user = (User) o;
-        return userID == user.userID;
+        return id == user.id;
     }
 
     @Override
     public int hashCode() {
-        return Objects.hash(userID);
+        return Objects.hash(id);
     }
 }