Index: oak-core/src/test/java/org/apache/jackrabbit/oak/security/user/RepMembersConflictHandlerTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-core/src/test/java/org/apache/jackrabbit/oak/security/user/RepMembersConflictHandlerTest.java	(revision 1853651)
+++ oak-core/src/test/java/org/apache/jackrabbit/oak/security/user/RepMembersConflictHandlerTest.java	(date 1550247180000)
@@ -24,7 +24,9 @@
 import org.apache.jackrabbit.api.security.user.UserManager;
 import org.apache.jackrabbit.oak.AbstractSecurityTest;
 import org.apache.jackrabbit.oak.api.Root;
+import org.apache.jackrabbit.oak.spi.security.ConfigurationParameters;
 import org.apache.jackrabbit.oak.spi.security.user.UserConstants;
+import org.jetbrains.annotations.NotNull;
 import org.junit.Test;
 
 public class RepMembersConflictHandlerTest extends AbstractSecurityTest {
@@ -43,6 +45,7 @@
         UserManager um = getUserManager(root);
         // create a group to receive users
         group = um.createGroup(GROUP_ID);
+        fillGroup(group);
         // create future members of the above group
         User u1 = um.createUser("u1", "pass");
         User u2 = um.createUser("u2", "pass");
@@ -53,6 +56,10 @@
         users = new User[] { u1, u2, u3, u4, u5 };
     }
 
+    void fillGroup(@NotNull Group group) throws Exception {
+        // nothing to do
+    }
+
     @Test
     public void addExistingProperty() throws Exception {
         Root ours = login(getAdminCredentials()).getLatestRoot();
Index: oak-core/src/test/java/org/apache/jackrabbit/oak/security/user/RepMembersConflictHandlerWithMemberSubtreeTest.java
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- oak-core/src/test/java/org/apache/jackrabbit/oak/security/user/RepMembersConflictHandlerWithMemberSubtreeTest.java	(date 1550247180000)
+++ oak-core/src/test/java/org/apache/jackrabbit/oak/security/user/RepMembersConflictHandlerWithMemberSubtreeTest.java	(date 1550247180000)
@@ -0,0 +1,57 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.jackrabbit.oak.security.user;
+
+import org.apache.jackrabbit.api.security.user.Group;
+import org.apache.jackrabbit.api.security.user.User;
+import org.apache.jackrabbit.api.security.user.UserManager;
+import org.apache.jackrabbit.oak.AbstractSecurityTest;
+import org.apache.jackrabbit.oak.api.Root;
+import org.apache.jackrabbit.oak.spi.security.ConfigurationParameters;
+import org.apache.jackrabbit.oak.spi.security.user.UserConfiguration;
+import org.apache.jackrabbit.oak.spi.security.user.UserConstants;
+import org.apache.jackrabbit.oak.spi.xml.ImportBehavior;
+import org.apache.jackrabbit.oak.spi.xml.ProtectedItemImporter;
+import org.jetbrains.annotations.NotNull;
+import org.junit.Test;
+
+import javax.jcr.RepositoryException;
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class RepMembersConflictHandlerWithMemberSubtreeTest extends RepMembersConflictHandlerTest {
+
+    @Override
+    protected ConfigurationParameters getSecurityConfigParameters() {
+        return ConfigurationParameters.of(UserConfiguration.NAME,
+                ConfigurationParameters.of(
+                        ProtectedItemImporter.PARAM_IMPORT_BEHAVIOR, ImportBehavior.NAME_BESTEFFORT)
+        );
+    }
+
+    @Override
+    void fillGroup(@NotNull Group group) throws Exception {
+        List<String> memberIds = new ArrayList<>();
+        for (int i = 0; i <= MembershipWriter.DEFAULT_MEMBERSHIP_THRESHOLD*2; i++) {
+            memberIds.add("member"+i);
+        }
+        assertTrue(group.addMembers(memberIds.toArray(new String[0])).isEmpty());
+    }
+}