Fix #1411

Author: cowtowncoder

release-notes/CREDITS

@@ -18,6 +18,8 @@ Joern Huxhorn: (huxi@github)
    (2.0.0)
   * Reported #479: NPE on trying to deserialize a `String[]` that contains null
    (2.4.1)
+  * Reported #1411: MapSerializer._orderEntries should check for null keys
+   (2.7.9)
 
 James Roper:
  * Requested [JACKSON-732]: Allow 'AnnotationIntrospector.findContentDeserializer()'

release-notes/VERSION

@@ -8,6 +8,8 @@ Project: jackson-databind
 
 #1392: Custom UnmodifiableSetMixin Fails in Jackson 2.7+ but works in Jackson 2.6
  (reported by Rob W)
+#1411: MapSerializer._orderEntries should check for null keys
+ (reported by Jörn H)
 
 2.7.8 (26-Sep-2016)
 

src/main/java/com/fasterxml/jackson/databind/ser/std/MapSerializer.java

@@ -933,7 +933,16 @@ protected Map<?,?> _orderEntries(Map<?,?> input)
         if (input instanceof SortedMap<?,?>) {
             return input;
         }
+        // [databind#1411]: TreeMap does not like null key...
+        if (input.containsKey(null)) {
+            TreeMap<Object,Object> result = new TreeMap<Object,Object>();
+            for (Map.Entry<?,?> entry : input.entrySet()) {
+                Object key = entry.getKey();
+                if (key != null) {
+                    result.put(key, entry.getValue());
+                }
+            }
+        }
         return new TreeMap<Object,Object>(input);
     }
 }
-