Program: 41902
Project: 41902
Buggy source:
@Test public void testJsonSerialization(){
  Document document=new Document();
  document.set("String_Node_Str",null);
  document.set("String_Node_Str","String_Node_Str");
  Document childDocument=new Document("String_Node_Str");
  document.set("String_Node_Str",childDocument);
  document.set("String_Node_Str",new JSONObject("String_Node_Str"));
  document.set("String_Node_Str",new StaticPOJOForTest());
  Collection<Integer> collection1=new ArrayList<Integer>();
  collection1.add(101);
  collection1.add(102);
  document.set("String_Node_Str",collection1);
  Collection<Document> collection2=new ArrayList<Document>();
  collection2.add(new Document("String_Node_Str"));
  document.set("String_Node_Str",collection2);
  Collection<StaticPOJOForTest> collection3=new ArrayList<StaticPOJOForTest>();
  collection3.add(new StaticPOJOForTest());
  document.set("String_Node_Str",collection3);
  Collection<Collection<Collection<String>>> collection4=new ArrayList<Collection<Collection<String>>>();
  Collection<Collection<String>> collection5=new ArrayList<Collection<String>>();
  Collection<String> collection6=new ArrayList<String>();
  collection6.add("String_Node_Str");
  collection5.add(collection6);
  collection4.add(collection5);
  document.set("String_Node_Str",collection4);
  Document expectedDocument=new Document("String_Node_Str" + "String_Node_Str" + "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str");
  Assert.assertEquals(expectedDocument.toString(),document.toString());
  Assert.assertEquals("String_Node_Str",document.getObject("String_Node_Str",StaticPOJOForTest.class).pojoProp);
  Assert.assertEquals("String_Node_Str",document.getCollection("String_Node_Str",StaticPOJOForTest.class).iterator().next().pojoProp);
  document=new Document("String_Node_Str");
  StaticPOJOForTest pojo=document.toObject(StaticPOJOForTest.class);
  Assert.assertEquals("String_Node_Str",pojo.pojoProp);
  JSONObject jsonObject=document.toObject(JSONObject.class);
  Assert.assertEquals("String_Node_Str",jsonObject.getString("String_Node_Str"));
}

Fixed version (ground truth):
@Test public void testJsonSerialization(){
  Document document=new Document();
  document.set("String_Node_Str",null);
  document.set("String_Node_Str","String_Node_Str");
  Document childDocument=new Document("String_Node_Str");
  document.set("String_Node_Str",childDocument);
  document.set("String_Node_Str",new JSONObject("String_Node_Str"));
  document.set("String_Node_Str",new StaticPOJOForTest());
  document.set("String_Node_Str",new AnotherPOJO());
  Collection<Integer> collection1=new ArrayList<Integer>();
  collection1.add(101);
  collection1.add(102);
  document.set("String_Node_Str",collection1);
  Collection<Document> collection2=new ArrayList<Document>();
  collection2.add(new Document("String_Node_Str"));
  document.set("String_Node_Str",collection2);
  Collection<StaticPOJOForTest> collection3=new ArrayList<StaticPOJOForTest>();
  collection3.add(new StaticPOJOForTest());
  document.set("String_Node_Str",collection3);
  Collection<Collection<Collection<String>>> collection4=new ArrayList<Collection<Collection<String>>>();
  Collection<Collection<String>> collection5=new ArrayList<Collection<String>>();
  Collection<String> collection6=new ArrayList<String>();
  collection6.add("String_Node_Str");
  collection5.add(collection6);
  collection4.add(collection5);
  document.set("String_Node_Str",collection4);
  Document expectedDocument=new Document("String_Node_Str" + "String_Node_Str" + "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str"+ "String_Node_Str");
  Assert.assertEquals(expectedDocument.toString(),document.toString());
  Assert.assertEquals("String_Node_Str",document.getObject("String_Node_Str",StaticPOJOForTest.class).pojoProp);
  Assert.assertEquals("String_Node_Str",document.getObject("String_Node_Str",AnotherPOJO.class).pojoProp);
  Assert.assertEquals("String_Node_Str",document.getCollection("String_Node_Str",StaticPOJOForTest.class).iterator().next().pojoProp);
  document=new Document("String_Node_Str");
  StaticPOJOForTest pojo=document.toObject(StaticPOJOForTest.class);
  Assert.assertEquals("String_Node_Str",pojo.pojoProp);
  JSONObject jsonObject=document.toObject(JSONObject.class);
  Assert.assertEquals("String_Node_Str",jsonObject.getString("String_Node_Str"));
}