DataObjectInfo should not throw NPE when it is not serializable

vertx-codegen-processor/src/main/java/io/vertx/codegen/type/DataObjectInfo.java

@@ -25,7 +25,13 @@ public boolean isAnnotated() {
   }
 
   public TypeInfo getJsonType() {
-    return deserializer != null ? deserializer.getJsonType() : serializer.getJsonType();
+    if (deserializer != null) {
+      return deserializer.getJsonType();
+    } else if (serializer != null) {
+      return serializer.getJsonType();
+    } else {
+      return null;
+    }
   }
 
   public MapperInfo getSerializer() {

vertx-codegen-processor/src/test/java/io/vertx/test/codegen/DataObjectTest.java

@@ -8,6 +8,7 @@
 import io.vertx.codegen.annotations.VertxGen;
 import io.vertx.codegen.doc.Doc;
 import io.vertx.codegen.type.*;
+import io.vertx.core.buffer.Buffer;
 import io.vertx.core.json.JsonArray;
 import io.vertx.core.json.JsonObject;
 import io.vertx.test.codegen.annotations.EmptyAnnotation;
@@ -951,4 +952,18 @@ private void assertInvalidDataObject(Class<?> dataObjectClass) throws Exception
     } catch (GenException ignore) {
     }
   }
+
+  @Test
+  public void testBuffer() throws Exception {
+    DataObjectModel model = new GeneratorHelper()
+      .generateDataObject(BufferHolder.class);
+    assertNotNull(model);
+    assertTrue(model.isClass());
+
+    PropertyInfo prop = model.getPropertyMap().get("buffer");
+    assertNotNull(prop);
+    assertFalse(prop.getType().getDataObject().isDeserializable());
+    assertFalse(prop.getType().getDataObject().isSerializable());
+    assertNull(prop.getType().getDataObject().getJsonType());
+  }
 }

vertx-codegen-processor/src/test/java/io/vertx/test/codegen/testdataobject/BufferHolder.java

@@ -0,0 +1,18 @@
+package io.vertx.test.codegen.testdataobject;
+
+import io.vertx.codegen.annotations.DataObject;
+import io.vertx.core.buffer.Buffer;
+
+@DataObject
+public class BufferHolder {
+
+  private Buffer buffer;
+
+  public Buffer getBuffer() {
+    return buffer;
+  }
+
+  public void setBuffer(Buffer buffer) {
+    this.buffer = buffer;
+  }
+}