The license statement on this plugin is very confusing:
Intellectual Property rights reserved byTodd Lahman, LLC as allowed by law incude,
but are not limited to, the working concept, function, and behavior of this plugin,
the logical code structure and expression as written. All WordPress functions, objects, and
related items, remain the property of WordPress under GPLv3 license, and any WordPress core
functions and objects in this plugin operate under the GPLv3 license.
Does that mean it's GPLv3? Or GPLv3 for some parts and not others (which seems very unlikely to be possible, given the GPLv3's copyleft provisions...)?
Meanwhile, the plugin appearson WordPress.org... but the WordPress.org licensing policy suggests that all plugin code is GPLv2 or later:
The license under which the WordPress software is released is the GPLv2 (or later) [...]
Part of this license outlines requirements for derivative works, such as plugins or themes. Derivatives of WordPress code inherit the GPL license. [...]
There is some legal grey area regarding what is considered a derivative work, but we feel strongly that plugins and themes are derivative work and thus inherit the GPL license. [...]
So, it seems like this plugin licensed under the GPLv3, as indicated by the "License: GPLv3" and by the WordPress GPLv2 (or later) license being subject to derivative works such as this plugin... correct?