Minor javadoc update

server-spi/src/main/java/org/keycloak/models/UserModel.java

@@ -57,7 +57,7 @@ public interface UserModel extends RoleMapperModel {
     void setEnabled(boolean enabled);
 
     /**
-     * Set single value of specified attribute. Remove all other existing values
+     * Set single value of specified attribute. Remove all other existing values of this attribute
      *
      * @param name
      * @param value