JAVA-1970: In DB.createCollection method, defer collection creation if options is null, as per documentation

Author: jyemin

driver/src/main/com/mongodb/DB.java

@@ -251,7 +251,9 @@ public String apply(final DBObject result) {
      * @mongodb.driver.manual reference/method/db.createCollection/ createCollection()
      */
     public DBCollection createCollection(final String collectionName, final DBObject options) {
-        executor.execute(getCreateCollectionOperation(collectionName, options));
+        if (options != null) {
+            executor.execute(getCreateCollectionOperation(collectionName, options));
+        }
         return getCollection(collectionName);
     }
 

driver/src/test/functional/com/mongodb/DBTest.java

@@ -117,6 +117,13 @@ public void shouldReceiveAnErrorIfCreatingCappedCollectionWithoutSize() {
         database.createCollection("someName", new BasicDBObject("capped", true));
     }
 
+    @Test
+    public void shouldDeferCollectionCreationIfOptionsIsNull() {
+        collection.drop();
+        database.createCollection(collectionName, null);
+        assertFalse(database.getCollectionNames().contains(collectionName));
+    }
+
     @Test
     public void shouldCreateCappedCollection() {
         collection.drop();