jsoniter how to prevent print null to json

I use Jsoniter to deserialize jsons and serialize objects to json. I have an object with many properties and add them as json member by @JsonProperty("xxx"). when use the following code for print json message of an object:

JsonStream.serialize(this);

I see members with null value in output. required:

{"title":"Clean Code","price":42}

but I see:

{"title":"Clean Code","author":null,"price":42}

How to prevent printing null members (author in this example) in Jsoniter? (something like @JsonInclude(Include.NON_NULL) in Jackson)