Here is an example of how to use the NullsConstantProvider class from the com.fasterxml.jackson.databind package in the Jackson library for Java:

import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationFeature;
import com.fasterxml.jackson.databind.util.NullsConstantProvider;

public class Example {
    public static void main(String[] args) throws Exception {
        ObjectMapper mapper = new ObjectMapper();
        mapper.setDefaultNullValueProvider(new NullsConstantProvider("N/A"));
        mapper.enable(SerializationFeature.WRITE_NULL_MAP_VALUES);
        mapper.enable(SerializationFeature.WRITE_EMPTY_JSON_ARRAYS);
        System.out.println(mapper.writeValueAsString(new MyObject()));
    }

    static class MyObject {
        public String name = null;
    }
}

This code creates an instance of the ObjectMapper class and sets it to use a NullsConstantProvider with the constant value of "N/A". It also enables the SerializationFeature.WRITE_NULL_MAP_VALUES and SerializationFeature.WRITE_EMPTY_JSON_ARRAYS features. Finally it serializes an instance of the MyObject class, which has a null value for the name property, and prints the resulting JSON string to the console.

The output of this code would be:

{"name":"N/A"}

You can change the default value of "N/A" to any other value you want.