diff --git a/astah/JSON.asta b/astah/JSON.asta
index fedf9e8..c37dfe7 100644
Binary files a/astah/JSON.asta and b/astah/JSON.asta differ
diff --git a/src/main/java/io/github/azige/json/JsonWriterImpl.java b/src/main/java/io/github/azige/json/JsonWriterImpl.java
index d51e5af..8762de3 100644
--- a/src/main/java/io/github/azige/json/JsonWriterImpl.java
+++ b/src/main/java/io/github/azige/json/JsonWriterImpl.java
@@ -15,7 +15,6 @@
  */
 package io.github.azige.json;
 
-import static javax.management.Query.value;
 
 import java.io.Writer;
 import java.util.Map.Entry;
diff --git a/src/test/java/io/github/azige/json/JsonGeneratorImplTest.java b/src/test/java/io/github/azige/json/JsonGeneratorImplTest.java
index b93caf4..4a6ba52 100644
--- a/src/test/java/io/github/azige/json/JsonGeneratorImplTest.java
+++ b/src/test/java/io/github/azige/json/JsonGeneratorImplTest.java
@@ -26,6 +26,7 @@
 import java.io.StringWriter;
 import java.util.Arrays;
 
+import javax.json.stream.JsonGenerator;
 
 /**
  *
@@ -71,7 +72,7 @@ public void testSomeMethod(){
     @Test
     public void testFormat(){
         StringWriter sw = new StringWriter();
-        JsonGeneratorImpl generator = new JsonGeneratorImpl(sw, true);
+        JsonGenerator generator = new JsonGeneratorImpl(sw, true);
         generator
             .writeStartObject()
             .write("firstName", "John")
@@ -96,7 +97,28 @@ public void testFormat(){
             .writeEnd()
             .close();
 
-        System.out.println(sw.toString());
+        String expect = "{\n"
+            + "    \"firstName\": \"John\",\n"
+            + "    \"lastName\": \"Smith\",\n"
+            + "    \"age\": 25,\n"
+            + "    \"address\": {\n"
+            + "        \"streetAddress\": \"21 2nd Street\",\n"
+            + "        \"city\": \"New York\",\n"
+            + "        \"state\": \"NY\",\n"
+            + "        \"postalCode\": \"10021\"\n"
+            + "    },\n"
+            + "    \"phoneNumber\": [\n"
+            + "        {\n"
+            + "            \"type\": \"home\",\n"
+            + "            \"number\": \"212 555-1234\"\n"
+            + "        },\n"
+            + "        {\n"
+            + "            \"type\": \"fax\",\n"
+            + "            \"number\": \"646 555-4567\"\n"
+            + "        }\n"
+            + "    ]\n"
+            + "}";
+        assertEquals(expect, sw.toString());
     }
 
     @Test