The SDK reference page for PluginCollection says that it implements the inherited methods Find, Filter, and GetAsText.
But it doesn’t. And according to the object hierarchy, it doesn’t have a base class (so where do those inherited methods come from 🙂
I can’t really remember anymore, but I think all the collection objects derive from a now-undocumented base class; or at least the documentation pretends they do (that made it simpler to auto-generate the pages). That’s why they all have inherited methods and properties, and they all have the same scripting examples.
Note: On a reference page, the yellow highlighting marks inherited methods and properties.