Changing password using the UnboundID LDAP SDK

PasswordChange.java

import com.unboundid.ldap.listener.InMemoryDirectoryServer;
import com.unboundid.ldap.listener.InMemoryDirectoryServerConfig;
import com.unboundid.ldap.listener.InMemoryListenerConfig;
import com.unboundid.ldap.sdk.*;
import com.unboundid.ldif.LDIFException;

/**
 * Sample code to demonstrate password change.
 * Error handling is not demonstrated here.
 */
public class PasswordChange {

    // Fields
    private InMemoryDirectoryServer server;

    private void setupServer() throws LDAPException, LDIFException {
        //
        // Setup/configure an in-memory LDAP server
        //
        InMemoryDirectoryServerConfig config =
                new InMemoryDirectoryServerConfig("dc=example,dc=com");

        // Configure admin user credentials
        config.addAdditionalBindCredentials("cn=Directory Manager", "password");

        // Configure an LDAP port
        config.setListenerConfigs(
                InMemoryListenerConfig.createLDAPConfig(
                        "LDAP", // Listener name
                        1389 // Listen port
                )
        );

        // Create and start the LDAP server
        server = new InMemoryDirectoryServer(config);
        server.startListening();

        // Populate the LDAP server with some data
        server.add(
                "dn: dc=example,dc=com",
                "objectClass: domain",
                "dc: example");

        server.add(
                "dn: uid=testuser,dc=example,dc=com",
                "objectClass: inetOrgPerson",
                "uid: testuser",
                "cn: Test User",
                "sn: User",
                "userPassword: abc123"
        );
    }

    public void changePassword(String user, String password) throws LDAPException {
        final LDAPConnection connection = server.getConnection();
        final String userDN;


        // Connect as the admin user
        connection.bind("cn=Directory Manager", "password");

        // The password is replaced with the new value
        Modification modification = new Modification(
                ModificationType.REPLACE,
                "userPassword",
                password
        );

        // The DN of the user
        userDN = "uid=" + user + ",dc=example,dc=com";

        // Build the modification request
        ModifyRequest modifyRequest = new ModifyRequest(
                userDN,
                modification
        );

        // Execute the modification
        connection.modify(modifyRequest);

        // Test the new password
        final LDAPConnection userConnection = server.getConnection();

        // Test the bind - if this fails, an exception is thrown
        userConnection.bind(userDN, password);

    }

    public void tearDown()
    {
        server.shutDown(true);
    }


    public static void main(String[] args) throws LDAPException, LDIFException {
        PasswordChange passwordChange = new PasswordChange();
        passwordChange.setupServer();
        passwordChange.changePassword("testuser", "testpassword");
        passwordChange.tearDown();
    }

}

I am getting the following error (am I missing ObjectClass?):

Exception in thread "main" LDAPException(resultCode=32 (no such object), diagnosticMessage='Unable to modify entry 'uid=prashantssadmin,cn=support-staff-admin,ou=canavans,dc=canavans,dc=local' because it does not exist in the server.', ldapSDKVersion=5.1.0, revision=89705d759f7c1ab3bccb2870f8c2e7d529ed231b)

because it does not exist in the server;;