Complete backporting of #407 for 2.3.3

Author: cowtowncoder

src/main/java/com/fasterxml/jackson/databind/deser/std/CollectionDeserializer.java

@@ -222,7 +222,7 @@ public Collection<Object> deserialize(JsonParser jp, DeserializationContext ctxt
             Object value;
 
             if (t == JsonToken.VALUE_NULL) {
-                value = null;
+                value = valueDes.getNullValue();
             } else if (typeDeser == null) {
                 value = valueDes.deserialize(jp, ctxt);
             } else {

src/main/java/com/fasterxml/jackson/databind/deser/std/StringCollectionDeserializer.java

@@ -184,7 +184,7 @@ private Collection<String> deserializeUsingCustom(JsonParser jp, Deserialization
             String value;
 
             if (t == JsonToken.VALUE_NULL) {
-                value = null;
+                value = deser.getNullValue();
             } else {
                 value = deser.deserialize(jp, ctxt);
             }
@@ -222,7 +222,7 @@ private final Collection<String> handleNonArray(JsonParser jp, DeserializationCo
         String value;
 
         if (t == JsonToken.VALUE_NULL) {
-            value = null;
+            value = (valueDes == null) ? null : valueDes.getNullValue();
         } else {
             value = (valueDes == null) ? _parseString(jp, ctxt) : valueDes.deserialize(jp, ctxt);
         }