Here is an example of how to use the RequestPayload class from the org.apache.commons.io package in Java:

import org.apache.commons.io.input.RequestPayload;
import java.io.IOException;
import java.io.InputStream;

public class Main {
    public static void main(String[] args) throws IOException {
        // Create a RequestPayload object with a String payload
        RequestPayload payload = new RequestPayload("Hello, World!");

        // Get the input stream from the payload
        InputStream inputStream = payload.getInputStream();
        //Read the input stream
        int data = inputStream.read();
        while(data != -1){
            System.out.print((char) data);
            data = inputStream.read();
        }
    }
}

In this example, we create a RequestPayload object with a payload of "Hello, World!" and we use the getInputStream() method to get the input stream of the payload and read the stream to print the payload.

It's worth noting that this class was removed from the apache.commons.io library in version 2.6 and later versions, you can use other libraries like ByteArrayInputStream and StringInputStream for similar functionality.