diff --git a/dspace-api/src/main/java/org/dspace/content/Collection.java b/dspace-api/src/main/java/org/dspace/content/Collection.java
index 8964b6767f..d4998156f0 100644
--- a/dspace-api/src/main/java/org/dspace/content/Collection.java
+++ b/dspace-api/src/main/java/org/dspace/content/Collection.java
@@ -12,13 +12,14 @@ import org.dspace.content.factory.ContentServiceFactory;
 import org.dspace.content.service.CollectionService;
 import org.dspace.core.*;
 import org.dspace.eperson.Group;
+import org.hibernate.annotations.CacheConcurrencyStrategy;
+import org.hibernate.annotations.Sort;
+import org.hibernate.annotations.SortType;
 import org.hibernate.proxy.HibernateProxyHelper;
 
 import javax.persistence.*;
 import java.sql.SQLException;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.List;
+import java.util.*;
 
 /**
  * Class representing a collection.
@@ -85,7 +86,8 @@ public class Collection extends DSpaceObject implements DSpaceObjectLegacySuppor
             joinColumns = {@JoinColumn(name = "collection_id") },
             inverseJoinColumns = {@JoinColumn(name = "community_id") }
     )
-    private final List<Community> communities = new ArrayList<>();
+    @Sort(type = SortType.COMPARATOR, comparator = NameAscendingComparator.class)
+    private Set<Community> communities = new TreeSet<>(new NameAscendingComparator());
 
     @Transient
     private transient CollectionService collectionService;
@@ -265,8 +267,8 @@ public class Collection extends DSpaceObject implements DSpaceObjectLegacySuppor
      */
     public List<Community> getCommunities() throws SQLException
     {
-        Collections.sort(communities, new NameAscendingComparator());
-        return communities;
+        // We return a copy because we do not want people to add elements to this collection directly.
+        return Arrays.asList(communities.toArray(new Community[]{}));
     }
 
     void addCommunity(Community community) {
@@ -348,4 +350,4 @@ public class Collection extends DSpaceObject implements DSpaceObjectLegacySuppor
         }
         return collectionService;
     }
-}
\ No newline at end of file
+}
diff --git a/dspace-api/src/main/java/org/dspace/content/CollectionServiceImpl.java b/dspace-api/src/main/java/org/dspace/content/CollectionServiceImpl.java
index dfa8f8e9b6..1e4b35e654 100644
--- a/dspace-api/src/main/java/org/dspace/content/CollectionServiceImpl.java
+++ b/dspace-api/src/main/java/org/dspace/content/CollectionServiceImpl.java
@@ -750,8 +750,8 @@ public class CollectionServiceImpl extends DSpaceObjectServiceImpl<Collection> i
         while (owningCommunities.hasNext())
         {
             Community owningCommunity = owningCommunities.next();
-            owningCommunities.remove();
-            owningCommunity.getCollections().remove(collection);
+            collection.removeCommunity(owningCommunity);
+            owningCommunity.removeCollection(collection);
         }
 
         collectionDAO.delete(context, collection);
diff --git a/dspace-api/src/main/java/org/dspace/content/Community.java b/dspace-api/src/main/java/org/dspace/content/Community.java
index 376a9283a5..9ecc5d7774 100644
--- a/dspace-api/src/main/java/org/dspace/content/Community.java
+++ b/dspace-api/src/main/java/org/dspace/content/Community.java
@@ -14,6 +14,9 @@ import org.dspace.content.factory.ContentServiceFactory;
 import org.dspace.content.service.CommunityService;
 import org.dspace.core.*;
 import org.dspace.eperson.Group;
+import org.hibernate.annotations.CacheConcurrencyStrategy;
+import org.hibernate.annotations.Sort;
+import org.hibernate.annotations.SortType;
 import org.hibernate.proxy.HibernateProxyHelper;
 
 import javax.persistence.*;
@@ -45,13 +48,16 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
             joinColumns = {@JoinColumn(name = "parent_comm_id") },
             inverseJoinColumns = {@JoinColumn(name = "child_comm_id") }
     )
-    private final List<Community> subCommunities = new ArrayList<>();
+    @Sort(type = SortType.COMPARATOR, comparator = NameAscendingComparator.class)
+    private Set<Community> subCommunities = new TreeSet<Community>(new NameAscendingComparator());
 
     @ManyToMany(fetch = FetchType.LAZY, mappedBy = "subCommunities")
-    private List<Community> parentCommunities = new ArrayList<>();
+    @Sort(type = SortType.COMPARATOR, comparator = NameAscendingComparator.class)
+    private Set<Community> parentCommunities = new TreeSet<Community>(new NameAscendingComparator());;
 
     @ManyToMany(fetch = FetchType.LAZY, mappedBy = "communities", cascade = {CascadeType.PERSIST})
-    private final List<Collection> collections = new ArrayList<>();
+    @Sort(type = SortType.COMPARATOR, comparator = NameAscendingComparator.class)
+    private Set<Collection> collections =new TreeSet<Collection>(new NameAscendingComparator());;
 
     @OneToOne
     @JoinColumn(name = "admin")
@@ -86,13 +92,13 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
 
     void addSubCommunity(Community subCommunity)
     {
-        getSubcommunities().add(subCommunity);
+        subCommunities.add(subCommunity);
         setModified();
     }
 
     void removeSubCommunity(Community subCommunity)
     {
-        getSubcommunities().remove(subCommunity);
+        subCommunities.remove(subCommunity);
         setModified();
     }
 
@@ -141,18 +147,18 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
      */
     public List<Collection> getCollections()
     {
-        Collections.sort(collections, new NameAscendingComparator());
-        return collections;
+        // We return a copy because we do not want people to add elements to this collection directly.
+        return Arrays.asList(collections.toArray(new Collection[]{}));
     }
 
     void addCollection(Collection collection)
     {
-        getCollections().add(collection);
+        collections.add(collection);
     }
 
     void removeCollection(Collection collection)
     {
-        getCollections().remove(collection);
+        collections.remove(collection);
     }
 
     /**
@@ -164,8 +170,8 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
      */
     public List<Community> getSubcommunities()
     {
-        Collections.sort(subCommunities, new NameAscendingComparator());
-        return subCommunities;
+        // We return a copy because we do not want people to add elements to this collection directly.
+        return Arrays.asList(subCommunities.toArray(new Community[]{}));
     }
 
     /**
@@ -176,12 +182,12 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
      */
     public List<Community> getParentCommunities()
     {
-        Collections.sort(parentCommunities, new NameAscendingComparator());
-        return parentCommunities;
+        // We return a copy because we do not want people to add elements to this collection directly.
+        return Arrays.asList(parentCommunities.toArray(new Community[]{}));
     }
 
     void addParentCommunity(Community parentCommunity) {
-        getParentCommunities().add(parentCommunity);
+        parentCommunities.add(parentCommunity);
     }
 
     void clearParentCommunities(){
@@ -189,6 +195,11 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
         this.parentCommunities = null;
     }
 
+    public void removeParentCommunity(Community parentCommunity)
+    {
+        this.parentCommunities.remove(parentCommunity);
+    }
+
     /**
      * Return <code>true</code> if <code>other</code> is the same Community
      * as this object, <code>false</code> otherwise
@@ -254,4 +265,4 @@ public class Community extends DSpaceObject implements DSpaceObjectLegacySupport
         }
         return communityService;
     }
-}
\ No newline at end of file
+}
diff --git a/dspace-api/src/main/java/org/dspace/content/CommunityServiceImpl.java b/dspace-api/src/main/java/org/dspace/content/CommunityServiceImpl.java
index 0002871a0a..f93e6d441c 100644
--- a/dspace-api/src/main/java/org/dspace/content/CommunityServiceImpl.java
+++ b/dspace-api/src/main/java/org/dspace/content/CommunityServiceImpl.java
@@ -455,7 +455,7 @@ public class CommunityServiceImpl extends DSpaceObjectServiceImpl<Community> imp
 
         rawDelete(context, childCommunity);
 
-        childCommunity.getParentCommunities().remove(parentCommunity);
+        childCommunity.removeParentCommunity(parentCommunity);
         parentCommunity.removeSubCommunity(childCommunity);
 
         log.info(LogManager.getHeader(context, "remove_subcommunity",
@@ -492,7 +492,7 @@ public class CommunityServiceImpl extends DSpaceObjectServiceImpl<Community> imp
             Iterator<Community> subcommunities = community.getSubcommunities().iterator();
             while (subcommunities.hasNext()) {
                 Community subCommunity = subcommunities.next();
-                subcommunities.remove();
+                community.removeSubCommunity(subCommunity);
                 delete(context, subCommunity);
             }
             // now let the parent remove the community
@@ -535,7 +535,7 @@ public class CommunityServiceImpl extends DSpaceObjectServiceImpl<Community> imp
         while (collections.hasNext())
         {
             Collection collection = collections.next();
-            collections.remove();
+            community.removeCollection(collection);
             removeCollection(context, community, collection);
         }
         // delete subcommunities
@@ -544,7 +544,7 @@ public class CommunityServiceImpl extends DSpaceObjectServiceImpl<Community> imp
         while (subCommunities.hasNext())
         {
             Community subComm = subCommunities.next();
-            subCommunities.remove();
+            community.removeSubCommunity(subComm);
             delete(context, subComm);
         }
 
diff --git a/dspace-api/src/main/java/org/dspace/content/Item.java b/dspace-api/src/main/java/org/dspace/content/Item.java
index e7a0a00a1e..aca2738d54 100644
--- a/dspace-api/src/main/java/org/dspace/content/Item.java
+++ b/dspace-api/src/main/java/org/dspace/content/Item.java
@@ -13,13 +13,12 @@ import org.dspace.content.service.ItemService;
 import org.dspace.core.Constants;
 import org.dspace.core.Context;
 import org.dspace.eperson.EPerson;
+import org.hibernate.annotations.Sort;
+import org.hibernate.annotations.SortType;
 import org.hibernate.proxy.HibernateProxyHelper;
 
 import javax.persistence.*;
-import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Date;
-import java.util.List;
+import java.util.*;
 
 /**
  * Class representing an item in DSpace.
@@ -80,7 +79,8 @@ public class Item extends DSpaceObject implements DSpaceObjectLegacySupport
             joinColumns = {@JoinColumn(name = "item_id") },
             inverseJoinColumns = {@JoinColumn(name = "collection_id") }
     )
-    private final List<Collection> collections = new ArrayList<>();
+    @Sort(type = SortType.COMPARATOR, comparator = NameAscendingComparator.class)
+    private final Set<Collection> collections = new TreeSet<>(new NameAscendingComparator());
 
     @ManyToMany(fetch = FetchType.LAZY, mappedBy = "items")
     private final List<Bundle> bundles = new ArrayList<>();
@@ -232,18 +232,22 @@ public class Item extends DSpaceObject implements DSpaceObjectLegacySupport
      */
     public List<Collection> getCollections()
     {
-        Collections.sort(collections, new NameAscendingComparator());
-        return collections;
+        // We return a copy because we do not want people to add elements to this collection directly.
+        return Arrays.asList(collections.toArray(new Collection[]{}));
     }
 
     void addCollection(Collection collection)
     {
-        getCollections().add(collection);
+        collections.add(collection);
     }
 
     void removeCollection(Collection collection)
     {
-        getCollections().remove(collection);
+        collections.remove(collection);
+    }
+
+    public void clearCollections(){
+        collections.clear();
     }
 
     public Collection getTemplateItemOf() {
diff --git a/dspace-api/src/main/java/org/dspace/content/ItemServiceImpl.java b/dspace-api/src/main/java/org/dspace/content/ItemServiceImpl.java
index 7ad0126236..c13ad27303 100644
--- a/dspace-api/src/main/java/org/dspace/content/ItemServiceImpl.java
+++ b/dspace-api/src/main/java/org/dspace/content/ItemServiceImpl.java
@@ -656,7 +656,7 @@ public class ItemServiceImpl extends DSpaceObjectServiceImpl<Item> implements It
         }
 
         //Only clear collections after we have removed everything else from the item
-        item.getCollections().clear();
+        item.clearCollections();
         item.setOwningCollection(null);
 
         // Finally remove item row