import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.*;
import java.io.IOException;

public class EmptyToNull extends JsonDeserializer<String> {

	@Override
	public String deserialize(JsonParser jsonParser, DeserializationContext context) throws IOException {
		JsonNode node = jsonParser.readValueAsTree();
		if (node.asText().isEmpty()) {
			return null;
		}
		return node.asText();
	}

}