diff --git a/scm-core/src/main/java/sonia/scm/security/SyncingRealmHelper.java b/scm-core/src/main/java/sonia/scm/security/SyncingRealmHelper.java
index 9a4ba8294e..a716544846 100644
--- a/scm-core/src/main/java/sonia/scm/security/SyncingRealmHelper.java
+++ b/scm-core/src/main/java/sonia/scm/security/SyncingRealmHelper.java
@@ -80,7 +80,7 @@ public final class SyncingRealmHelper {
    * @param ctx          administration context
    * @param userManager  user manager
    * @param groupManager group manager
-   * @deprecated
+   * @deprecated Use the other constructor including {@link ExternalUserConverter} instead.
    */
   @Deprecated
   public SyncingRealmHelper(AdministrationContext ctx, UserManager userManager, GroupManager groupManager) {
diff --git a/scm-core/src/main/java/sonia/scm/user/ExternalUserConverter.java b/scm-core/src/main/java/sonia/scm/user/ExternalUserConverter.java
index 47f0be8312..5fa5579b88 100644
--- a/scm-core/src/main/java/sonia/scm/user/ExternalUserConverter.java
+++ b/scm-core/src/main/java/sonia/scm/user/ExternalUserConverter.java
@@ -26,14 +26,18 @@ package sonia.scm.user;
 
 import sonia.scm.plugin.ExtensionPoint;
 
+/**
+ * The external user converter can be used to modify users
+ * which are provided by external systems before creation in SCM-Manager.
+ * The implementations will be called in the {@link sonia.scm.security.SyncingRealmHelper}
+ * @since 2.9.0
+ */
 @ExtensionPoint
 public interface ExternalUserConverter {
 
   /**
    * Returns the converted user.
-   *
    * @return converted user
-   * @since 2.9.0
    */
   User convert(User user);
 }
diff --git a/scm-core/src/main/java/sonia/scm/user/User.java b/scm-core/src/main/java/sonia/scm/user/User.java
index 849321013a..e93b3d6ee4 100644
--- a/scm-core/src/main/java/sonia/scm/user/User.java
+++ b/scm-core/src/main/java/sonia/scm/user/User.java
@@ -167,7 +167,7 @@ public class User extends BasicPropertiesAware implements Principal, ModelObject
     return Objects.equal(name, other.name)
       && Objects.equal(displayName, other.displayName)
       && Objects.equal(mail, other.mail)
-      && Objects.equal(type, other.type)
+      && Objects.equal(external, other.external)
       && Objects.equal(active, other.active)
       && Objects.equal(password, other.password)
       && Objects.equal(creationDate, other.creationDate)
@@ -177,8 +177,8 @@ public class User extends BasicPropertiesAware implements Principal, ModelObject
 
   @Override
   public int hashCode() {
-    return Objects.hashCode(name, displayName, mail, type, password,
-      active, creationDate, lastModified, properties);
+    return Objects.hashCode(name, displayName, mail, password,
+      active, external, creationDate, lastModified, properties);
   }
 
   @Override
@@ -195,6 +195,7 @@ public class User extends BasicPropertiesAware implements Principal, ModelObject
       .add("password", pwd)
       .add("type", type)
       .add("active", active)
+      .add("external", external)
       .add("creationDate", creationDate)
       .add("lastModified", lastModified)
       .add("properties", properties)
@@ -205,7 +206,6 @@ public class User extends BasicPropertiesAware implements Principal, ModelObject
   @Override
   public boolean isValid() {
     return ValidationUtil.isNameValid(name) && Util.isNotEmpty(displayName)
-      && Util.isNotEmpty(type)
       && ((Util.isEmpty(mail)) || ValidationUtil.isMailAddressValid(mail));
   }