The documentation for the community extensions doesn't seem like it has been updated in a while so I was taking a look. One of the extension methods I am interested in is IsOptionExpiry but it appears to have a bug. It looks as though it doesn't take holidays into account and instead primarily just considers Fridays as expirations.

Are these community extensions open sourced somewhere so I can submit a bug fix?

and/or

Can I request an overload that accepts a bool for whether only monthly expirations should be considered?

QUOTE:
Are these community extensions open sourced somewhere so I can submit a bug fix?

You're welcome to submit a bug fix. Yes, it's open sourced in the Wiki:

Home - Community Components

To get it, register in the Wiki and I'll entitle your new account to access this content promptly.

Are there really any Friday holidays on the 3rd Friday of the month? Have there ever been?

For weekly options, sure, but I can't think of any 3rd Friday of a month being a holiday - which doesn't mean there isn't one!

Yes, in 2019 for example:

https://www.marketwatch.com/optionscenter/calendar/2019

Must be Good Friday. Thanks.

How do I go about submitting a bug fix? Just attach a file to this forum post? Is there a git repo?

Also, are there any unit tests? I made some small improvements to DateTimeEx.cs but I don't have a good way to verify my changes.

Simply create a support ticket and attach your code (in zip). Thanks!

QUOTE:
Is there a git repo?

It's a good idea. Need to investigate.