要約

As described in Delete or Disable Users under section "How deleted users appear to other people", once a user account has been deleted their identity will be anonymised and their full names will be replaced with an alias. 

This document explains how that new alias is generated. 

ソリューション

When a user is anonymised, their usernames will be replaced by the user_key and the Full Name of the user will be replaced by an alias like "user-{vwxyz}". 

This {vwxyz} value is derived from the user_key, calculating the SHA-256 digest in hexadecimal, and taking only the first 5 characters out of the result. 

The following code is a simple snippet of how this alias can be calculated for any of your users: 

package DeletedAlias;

import java.nio.charset.StandardCharsets;
import static org.apache.commons.codec.digest.DigestUtils.sha256Hex;

public class DeletedAlias {

	public static void main(String[] args) {
		
		String userKeyString = "<USER_KEY_OF_YOUR_USER>";         
                String userKeyHash = sha256Hex(userKeyString.getBytes(StandardCharsets.UTF_8));
                System.out.println("user-" + userKeyHash.substring(0, 5));

	}

}