1 files changed, 1 insertions, 0 deletions
diff --git a/document/src/main/java/com/yahoo/document/DocumentType.java b/document/src/main/java/com/yahoo/document/DocumentType.java
index a616c853bf4..08b0fe94046 100755
--- a/document/src/main/java/com/yahoo/document/DocumentType.java
+++ b/document/src/main/java/com/yahoo/document/DocumentType.java
@@ -13,6 +13,7 @@ import java.util.ArrayList;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;