diff --git a/genson-scala/src/main/scala/com/owlike/genson/ext/json4s/Json4SBundle.scala b/genson-scala/src/main/scala/com/owlike/genson/ext/json4s/Json4SBundle.scala
index dfaebe0a..457e51c9 100644
--- a/genson-scala/src/main/scala/com/owlike/genson/ext/json4s/Json4SBundle.scala
+++ b/genson-scala/src/main/scala/com/owlike/genson/ext/json4s/Json4SBundle.scala
@@ -13,7 +13,7 @@ import org.json4s.JsonAST.JDecimal
 import org.json4s.JsonAST.JArray
 import scala.collection.mutable.ArrayBuffer
 
-object Json4SBundle extends GensonBundle {
+class Json4SBundle extends GensonBundle {
 
   def configure(builder: GensonBuilder) {
     builder.withConverterFactory(new Factory[Converter[JValue]]() {
@@ -22,6 +22,10 @@ object Json4SBundle extends GensonBundle {
   }
 }
 
+object Json4SBundle {
+  def apply() = new Json4SBundle()
+}
+
 object JValueConverter extends Converter[JValue] {
 
   def serialize(value: JValue, writer: ObjectWriter, ctx: Context) = {
diff --git a/genson-scala/src/test/scala/com/owlike/genson/ext/json4s/Json4SRoundTripTest.scala b/genson-scala/src/test/scala/com/owlike/genson/ext/json4s/Json4SRoundTripTest.scala
index ca1c394e..e075b3ac 100644
--- a/genson-scala/src/test/scala/com/owlike/genson/ext/json4s/Json4SRoundTripTest.scala
+++ b/genson-scala/src/test/scala/com/owlike/genson/ext/json4s/Json4SRoundTripTest.scala
@@ -4,12 +4,12 @@ import org.scalatest.{Matchers, FunSuite}
 import com.owlike.genson.{ScalaBundle, GensonBuilder, ScalaGenson}
 import org.json4s._
 import org.json4s.JsonDSL._
-import org.json4s.JsonAST.{JValue, JNull}
+import org.json4s.JsonAST._
 
 class Json4SRoundTripTest extends FunSuite with Matchers {
   val genson = new ScalaGenson(
     new GensonBuilder()
-      .withBundle(ScalaBundle(), Json4SBundle)
+      .withBundle(ScalaBundle(), Json4SBundle())
       .create()
   )
 
diff --git a/genson/src/main/java/com/owlike/genson/convert/ClassMetadataConverter.java b/genson/src/main/java/com/owlike/genson/convert/ClassMetadataConverter.java
index dcdc88c2..fc1d7ced 100644
--- a/genson/src/main/java/com/owlike/genson/convert/ClassMetadataConverter.java
+++ b/genson/src/main/java/com/owlike/genson/convert/ClassMetadataConverter.java
@@ -66,8 +66,7 @@ public ClassMetadataConverter(Class<T> tClass, Converter<T> delegate) {
   }
 
   public void serialize(T obj, ObjectWriter writer, Context ctx) throws Exception {
-    // obj != null allows to not fail in case when the NullConverter is not in the chain
-    if (!Object.class.equals(tClass) && obj != null) {
+    if (obj != null) {
       writer.beginNextObjectMetadata()
         .writeMetadata("class", ctx.genson.aliasFor(obj.getClass()));
     }
diff --git a/website/Documentation/Extensions.md b/website/Documentation/Extensions.md
index 4b914438..a2215c8c 100644
--- a/website/Documentation/Extensions.md
+++ b/website/Documentation/Extensions.md
@@ -65,7 +65,17 @@ public class GensonCustomResolver implements ContextResolver<Genson> {
 
 **Note**
 
-By default Genson JAX-RS integration enables JAXB annotations support.
+* By default Genson JAX-RS integration enables JAXB annotations support.
+* Starting with Jersey 2.9, automatic discovery is disabled, in order to enable it like in previous versions you need
+ to a dependency to jersey-metainf-services.
+
+{% highlight xml %}
+<dependency>
+  <groupId>org.glassfish.jersey.ext</groupId>
+  <artifactId>jersey-metainf-services</artifactId>
+  <version>your_version</version>
+</dependency>
+{% endhighlight %}
 
 
 ##JSR 353 - Java API for Json Processing##
diff --git a/website/Documentation/ScalaGuide.md b/website/Documentation/ScalaGuide.md
index 171fb11b..eeee7c40 100644
--- a/website/Documentation/ScalaGuide.md
+++ b/website/Documentation/ScalaGuide.md
@@ -168,4 +168,52 @@ toJson(...)
 fromJson[SomeType](json)
 {% endhighlight %}
 
-For a more in depth overview of Genson features and customization have a look at the User Guide and configuration sections.
\ No newline at end of file
+For a more in depth overview of Genson features and customization have a look at the User Guide and configuration sections.
+
+
+##AST support via json4s
+
+Instead of creating again another DOM structure like all the existing ones, Genson provides it by supporting json4s.
+Json4s defines an AST for JSON and utilities to work with it.
+
+
+{% highlight scala %}
+import com.owlike.genson._
+import org.json4s._
+import org.json4s.JsonDSL._
+import org.json4s.JsonAST._
+
+object CustomGenson {
+  val genson = new ScalaGenson(
+    new GensonBuilder()
+      .withBundle(ScalaBundle(), Json4SBundle())
+    .create()
+  )
+}
+
+// then just import it in the places you want to use this instance instead of the default one
+import CustomGenson.genson._
+
+// and use it!
+val json = fromJson[JValue]("""{"name":"foo","someDouble":28.1,"male":true,"someArray":[1,2,3],"null":null}""")
+
+{% endhighlight %}
+
+
+In order to use json4s features with Genson, you need to add a dependency to it.
+
+###SBT
+
+{% highlight scala %}
+libraryDependencies += "org.json4s" % "json4s-ast_${scala.version}" % "3.2.10"
+{% endhighlight %}
+
+###Maven
+
+{% highlight xml %}
+<dependency>
+	<groupId>org.json4s</groupId>
+	<artifactId>json4s-ast_${scala.version}</artifactId>
+	<version>${json4s.version}</version>
+</dependency>
+{% endhighlight %}