@Override
    public void setPassword(String username, String password) throws UserNotFoundException, UnsupportedOperationException
    {
        final AuthProvider provider = getAuthProvider(username);
        if (provider == null)
        {
            throw new UserNotFoundException();
        }
        provider.setPassword( username, password );
    }
Returns the 'backing' provider that serves the provided user.

Finds a suitable AuthProvider for the user.

Unlike other MultiProvider interfaces, this interface does not require this method to return a non-null value.

@param username A user identifier (cannot be null or empty).
@return A AuthProvider for the user (possibly null).
xmppserver/src/main/java/org/jivesoftware/openfire/auth/AuthMultiProvider.java