diff --git a/rm-community/rm-community-repo/source/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtils.java b/rm-community/rm-community-repo/source/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtils.java
index 81e9652d72..6b1643f7fa 100644
--- a/rm-community/rm-community-repo/source/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtils.java
+++ b/rm-community/rm-community-repo/source/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtils.java
@@ -37,6 +37,8 @@ import java.util.List;
 import java.util.Map;
 import java.util.Set;
 
+import com.google.common.collect.ImmutableSet;
+
 /**
  * Various common helper methods for Collections. This class is probably only appropriate for use with relatively
  * small collections as it has not been optimised for dealing with large collections.
@@ -201,4 +203,27 @@ public final class RMCollectionUtils
             else                     { return Difference.UNCHANGED; }
         }
     }
+
+    /**
+     * Convert a collection to an immutable set. Any instances of null in the original collection will be removed.
+     *
+     * @param collection The original collection.
+     * @param <T> The type of the object in the collection.
+     * @return The immutable set.
+     */
+    public static <T> ImmutableSet<T> toImmutableSet(Collection<T> collection)
+    {
+        if (collection == null)
+        {
+            return null;
+        }
+        // Guava immutable collections can't contain null.
+        if (collection.contains(null))
+        {
+            // Make sure we're not changing the original collection (which might not be editable anyway).
+            collection = new HashSet<>(collection);
+            collection.remove(null);
+        }
+        return ImmutableSet.copyOf(collection);
+    }
 }
diff --git a/rm-community/rm-community-repo/unit-test/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtilsUnitTest.java b/rm-community/rm-community-repo/unit-test/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtilsUnitTest.java
index c7f2ede934..490dba4248 100644
--- a/rm-community/rm-community-repo/unit-test/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtilsUnitTest.java
+++ b/rm-community/rm-community-repo/unit-test/java/org/alfresco/module/org_alfresco_module_rm/util/RMCollectionUtilsUnitTest.java
@@ -46,6 +46,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 
 import org.alfresco.module.org_alfresco_module_rm.util.RMCollectionUtils.Difference;
 import org.junit.Test;
@@ -122,4 +123,21 @@ public class RMCollectionUtilsUnitTest
 
         assertEquals(s, l);
     }
+
+    @Test public void toImmutableSet_nullInput()
+    {
+        Set<String> output = RMCollectionUtils.toImmutableSet(null);
+        assertNull("toImmutableSet should pass through with null.", output);
+    }
+
+    @Test public void toImmutableSet_nullElement()
+    {
+        Set<String> input = newHashSet("One", null, "Three");
+
+        // Call the method under test.
+        Set<String> output = RMCollectionUtils.toImmutableSet(input);
+
+        assertEquals("Unexpected handling of null input element", output, newHashSet("One", "Three"));
+        assertEquals("Input should not have been changed.", input, newHashSet("One", null, "Three"));
+    }
 }