Get annotated methods with custom Gradle plugin

I'm trying to create a custom Gradle plugin that reads all classes based on an annotation. My urlclassloader is working, based on the basepackage I provide with the plugin, but when I use the getMethods() function, I get a ClassNotFoundException.

This is because some of the methods have parameters that are in third party dependencies. Is there a way to use all the dependencies of the project that is using the plugin? I want to deserialize them by using the objectmapper