Added CCC and close notify capabilities

[b-wagner]

Added clear command channel (CCC) and close notify support, based off of our forked revisions that we use with our ftpserver fork.

[b-wagner]

This entire 'if' block was originally commented out in our fork, citing issues with CCC and close notify. To not break backwards compatibility, I added the addition check for CCC enabled.

[elecharny]

Hi!

I'll review the proposed change soon.

Thanks!

[elecharny]

Thanks for the commit. I'll review it soon.

[maartenbosteels]

This PR looks good to me but I did not see test cases for the altered behavior in:

• org.apache.mina.filter.ssl.SslFilter#filterWrite
• org.apache.mina.filter.ssl.SslFilter#messageReceived
• org.apache.mina.filter.ssl.SslFilter#filterWrite
• org.apache.mina.filter.ssl.SslHandler#checkStatus

[elecharny]

Hi @maartenbosteels, do you feel like merging the PR, even with the missing test cases?

[maartenbosteels]

Hi @elecharny , how are you?

Yes, I think it's safe.
And CoPilot has assisted me to write some tests. Some are a bit trivial (like testing getters and setters) but the others are fine. Can I easily update the PR?
It's been a while ;-)

[elecharny]

Hi @maartenbosteels !

going very well :-) I hope you also do well !

Yes, please, go ahead with the PR and merge it!