diff --git a/src/main/java/org/olat/core/util/nodes/GenericNode.java b/src/main/java/org/olat/core/util/nodes/GenericNode.java
index 98a16686a0e72be1692650934aa5317ef97c9547..a8bc87d62f3ec1a2f3e01dc126c6b1c37271301b 100644
--- a/src/main/java/org/olat/core/util/nodes/GenericNode.java
+++ b/src/main/java/org/olat/core/util/nodes/GenericNode.java
@@ -28,14 +28,13 @@ package org.olat.core.util.nodes;
 
 import java.io.Serializable;
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 
 import org.olat.core.logging.AssertException;
 import org.olat.core.util.CodeHelper;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  * Description: <br>
  * 
diff --git a/src/main/java/org/olat/modules/docpool/ui/DocumentPoolAdminPermissionsController.java b/src/main/java/org/olat/modules/docpool/ui/DocumentPoolAdminPermissionsController.java
index ebc2a6c463769b373968ad1d0de31cdb28c9e650..790fbfaa7edf961ff62e2134fc77ba4b87295c01 100644
--- a/src/main/java/org/olat/modules/docpool/ui/DocumentPoolAdminPermissionsController.java
+++ b/src/main/java/org/olat/modules/docpool/ui/DocumentPoolAdminPermissionsController.java
@@ -20,6 +20,7 @@
 package org.olat.modules.docpool.ui;
 
 import java.util.ArrayList;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Set;
@@ -36,8 +37,6 @@ import org.olat.modules.taxonomy.TaxonomyRef;
 import org.olat.modules.taxonomy.TaxonomyService;
 import org.springframework.beans.factory.annotation.Autowired;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  * 
  * Initial date: 13 nov. 2017<br>
diff --git a/src/main/java/org/olat/modules/lecture/ui/CloseRollCallConfirmationController.java b/src/main/java/org/olat/modules/lecture/ui/CloseRollCallConfirmationController.java
index 53e7e7f48125894f95e4b84c3fb6839b25ff63fe..2fa7ef3eab44d6575f011c89d066cf48753f1c96 100644
--- a/src/main/java/org/olat/modules/lecture/ui/CloseRollCallConfirmationController.java
+++ b/src/main/java/org/olat/modules/lecture/ui/CloseRollCallConfirmationController.java
@@ -21,6 +21,7 @@ package org.olat.modules.lecture.ui;
 
 import java.util.ArrayList;
 import java.util.Calendar;
+import java.util.Collections;
 import java.util.Date;
 import java.util.List;
 
@@ -50,8 +51,6 @@ import org.olat.modules.lecture.Reason;
 import org.olat.modules.lecture.RollCallSecurityCallback;
 import org.springframework.beans.factory.annotation.Autowired;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  * 
  * Initial date: 12 juin 2017<br>
diff --git a/src/main/java/org/olat/modules/lecture/ui/export/AbstractLectureBlockAuditLogExport.java b/src/main/java/org/olat/modules/lecture/ui/export/AbstractLectureBlockAuditLogExport.java
index 78c56359e398e3b46b7ddc9c49a4bc090fea9534..91cc232d30a66477e27075e8872bde4f6f6f2753 100644
--- a/src/main/java/org/olat/modules/lecture/ui/export/AbstractLectureBlockAuditLogExport.java
+++ b/src/main/java/org/olat/modules/lecture/ui/export/AbstractLectureBlockAuditLogExport.java
@@ -21,6 +21,7 @@ package org.olat.modules.lecture.ui.export;
 
 import java.io.IOException;
 import java.io.OutputStream;
+import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
 import java.util.List;
@@ -44,8 +45,6 @@ import org.olat.repository.RepositoryEntry;
 import org.olat.repository.RepositoryManager;
 import org.olat.user.UserManager;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  * 
  * 
diff --git a/src/main/java/org/olat/modules/lecture/ui/export/LecturesBlockPDFExport.java b/src/main/java/org/olat/modules/lecture/ui/export/LecturesBlockPDFExport.java
index 4552e7613a20148858e99cd8318a1c797b0152a1..4820e04e76a5487c1533795e0bf41c6898532007 100644
--- a/src/main/java/org/olat/modules/lecture/ui/export/LecturesBlockPDFExport.java
+++ b/src/main/java/org/olat/modules/lecture/ui/export/LecturesBlockPDFExport.java
@@ -21,6 +21,7 @@ package org.olat.modules.lecture.ui.export;
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -46,8 +47,6 @@ import org.olat.modules.lecture.LectureBlock;
 import org.olat.modules.lecture.LectureBlockRollCall;
 import org.olat.repository.RepositoryEntry;
 
-import edu.emory.mathcs.backport.java.util.Arrays;
-
 /**
  * 
  * Initial date: 22 juin 2017<br>
diff --git a/src/main/java/org/olat/modules/qpool/ui/QuestionItemAuditLogExport.java b/src/main/java/org/olat/modules/qpool/ui/QuestionItemAuditLogExport.java
index af1fdb320d6f5e4c51c104a7717669eb92fd05f6..f3d22790222ed96968b4d1b69ca7d64e6eb74043 100644
--- a/src/main/java/org/olat/modules/qpool/ui/QuestionItemAuditLogExport.java
+++ b/src/main/java/org/olat/modules/qpool/ui/QuestionItemAuditLogExport.java
@@ -22,6 +22,7 @@ package org.olat.modules.qpool.ui;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.math.BigDecimal;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.Date;
 import java.util.List;
@@ -46,8 +47,6 @@ import org.olat.modules.qpool.ui.metadata.MetaUIFactory;
 import org.olat.modules.qpool.ui.metadata.MetaUIFactory.KeyValues;
 import org.olat.user.UserManager;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  * 
  * Initial date: 23.01.2018<br>
diff --git a/src/main/java/org/olat/modules/taxonomy/manager/TaxonomyLevelDAO.java b/src/main/java/org/olat/modules/taxonomy/manager/TaxonomyLevelDAO.java
index f94e8254ddb222d41500396557eeba15c9547bea..10df40fa37f1d893db27f11cbdd1c4edf1fe798a 100644
--- a/src/main/java/org/olat/modules/taxonomy/manager/TaxonomyLevelDAO.java
+++ b/src/main/java/org/olat/modules/taxonomy/manager/TaxonomyLevelDAO.java
@@ -21,6 +21,7 @@ package org.olat.modules.taxonomy.manager;
 
 import java.io.File;
 import java.nio.file.Path;
+import java.util.Collections;
 import java.util.Comparator;
 import java.util.Date;
 import java.util.List;
@@ -48,8 +49,6 @@ import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  * 
  * Initial date: 22 sept. 2017<br>
diff --git a/src/test/java/org/olat/resource/accesscontrol/provider/auto/manager/IdentifierHandlerTest.java b/src/test/java/org/olat/resource/accesscontrol/provider/auto/manager/IdentifierHandlerTest.java
index 1c659235fea27c36ae91724601f123250816c1c9..564bb2702d1c3264b4d89f0ed7c71a91be2da20a 100644
--- a/src/test/java/org/olat/resource/accesscontrol/provider/auto/manager/IdentifierHandlerTest.java
+++ b/src/test/java/org/olat/resource/accesscontrol/provider/auto/manager/IdentifierHandlerTest.java
@@ -26,6 +26,7 @@ import static org.mockito.Mockito.when;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 import org.junit.Before;
@@ -37,8 +38,6 @@ import org.mockito.Spy;
 import org.olat.repository.RepositoryEntry;
 import org.olat.resource.accesscontrol.provider.auto.IdentifierKey;
 
-import edu.emory.mathcs.backport.java.util.Collections;
-
 /**
  *
  * Initial date: 14.08.2017<br>