public void enableAccount(String username) throws UnsupportedOperationException {
        if (provider.isReadOnly()) {
            throw new UnsupportedOperationException();
        }
        provider.unsetDisabledStatus(username);
        if (!provider.shouldNotBeCached()) {
            // Remove lockout data from cache.
            lockOutCache.remove(username);
        }
        // Fire event.
        LockOutEventDispatcher.accountUnlocked(username);
    }
Enables an account that may or may not have previously been disabled.  This erases any
knowledge of a lockout, including one that wasn't necessarily in effect at the time the
method was called.

@param username User to enable.
@throws UnsupportedOperationException if the provider is readonly.
xmppserver/src/main/java/org/jivesoftware/openfire/lockout/LockOutManager.java