plugins {
    java
}

interface CustomSourceSetConvention {
    val someOption: Property<String>
}

(sourceSets["main"].extensions as Convention).plugins["custom"] = objects.newInstance<CustomSourceSetConvention>()

// tag::source-set-convention[]
sourceSets {
    main {
        withConvention(CustomSourceSetConvention::class) {
            someOption = "some value"
        }
    }
}

import org.gradle.internal.reflect.JavaMethod
import spock.lang.Specification

class InstanceOptionDescriptorSpec extends Specification{

    OptionElement optionElement = optionElement("someOption")

    def testGetAvailableValuesWithNoDefaults() {
        given:
        optionElement.getAvailableValues() >> []

        when:

}

class NoParams implements SomeAction<Nothing> {
}

class BaseParams implements SomeAction<SomeParams> {
}

class RawActionType implements SomeAction {
}

class ComplexParameterizedType<A extends CustomParamsWithType<?>, B extends A, C extends B> implements SomeAction<C> {
}

class ParameterizedType<T extends CustomParams> implements SomeAction<T> {
}