where to add PlaceholderExpansion

[solid narwhal]

I am creating my own expansion using IntelliJ and I have a silly question:
How do I add the PlaceholderExpansion class to my project? Should I load it as a library, a module, or a JAR file?

I added the dependency in the pom file.

[hard eagle]

sorry to interrupt, but #development would be a better choice