Java – Jackson ObjectMapper cannot deserialize POJO, throws an exception: No suitable constructor found for type […]: can not instantiate from JSON object

I have tried to test the following code with no success:

class TestClass
{
  private class ND2Customer
  {
    public String name;
    public String description;
    public String email;
    public Boolean multiuser;

    public String dnszone;
    public String uri;
    public String type;

    public ND2Customer()
    {

    }
  }

  @Test
  public void TestJackson() throws JsonParseException, JsonMappingException, IOException
  {
    String json="{\"description\": \"test1u\", \"dnszone\": \"test1.public.sevenltest.example.com.\", \"uri\": \"http://199.127.129.69/customer/test1\", \"multiuser\": true, \"type\": \"2.0.3-3146\", \"email\": \"test1@com.com\", \"name\": \"test1\"}";
    ObjectMapper mapper = new ObjectMapper();

    ND2Customer casted=mapper.readValue(json, ND2Customer.class);

    String castedback=mapper.defaultPrettyPrintingWriter().writeValueAsString(casted);
    System.out.println(castedback);
  } 
}

This problem is different from this one:
Deserializing JSON with Jackson – Why JsonMappingException "No suitable constructor"?

and this one:
JsonMappingException: No suitable constructor found for type [simple type, class ]: can not instantiate from JSON object

and this one:
JsonMappingException: No suitable constructor found for type [simple type, class ]: can not instantiate from JSON object

as I have manually override the default constructor, and its not a subclass.

How do I fix this problem?