@Override
    public void setModificationDate(String username, Date modificationDate) throws UserNotFoundException
    {
        getUserProvider(username).setModificationDate(username, modificationDate);
    }
Changes the modification date of a user in the first provider that contains the user.

@param username the identifier of the user.
@param modificationDate the date the user was (last) modified.
@throws UserNotFoundException when the user was not found in any provider.
@throws UnsupportedOperationException when the provider is read-only.
xmppserver/src/main/java/org/jivesoftware/openfire/user/UserMultiProvider.java