Here is an example of how to use the JsonRawValue class from the Apache Commons IO library to serialize a POJO to JSON and include a raw JSON value within it:

import org.apache.commons.io.output.JsonStringEncoder;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.annotation.JsonSerialize;

public class Example {

    public static class MyPojo {

        private String name;

        @JsonSerialize(using = JsonRawValueSerializer.class)
        private String jsonData;

        // getters and setters
    }

    public static void main(String[] args) throws Exception {
        MyPojo pojo = new MyPojo();
        pojo.setName("John Doe");
        pojo.setJsonData("{\"key\":\"value\"}");

        ObjectMapper mapper = new ObjectMapper();
        String json = mapper.writeValueAsString(pojo);
        System.out.println(json);
    }

    public static class JsonRawValueSerializer extends JsonSerializer<String> {
        @Override
        public void serialize(String value, JsonGenerator gen, SerializerProvider serializers) throws IOException {
            gen.writeRawValue(value, JsonStringEncoder.getInstance());
        }
    }
}

This will output the following JSON:

{
    "name": "John Doe",
    "jsonData": {"key":"value"}
}

Note: This is using the Jackson JSON library to serialize the POJO to JSON. You need to have the jackson-databind jar in your classpath for this to work.