Method <org.gradle.api.DomainObjectCollection.matching(groovy.lang.Closure)> has arguments/return type groovy.lang.Closure that is not Gradle public API or primitive or built-in JDK classes or Kotlin classes in (DomainObjectCollection.java:0)

    id 'war'
}

webAppDirName = 'src/main/webapp' // Accessing a convention
----
=====
====

Clients should configure the `war` task  directly.
Also, link:{javadocPath}/org/gradle/api/DomainObjectCollection.html#withType-java.lang.Class-[tasks.withType(War.class).configureEach(...)] can be used to configure each task of type `War`.

====
[.multi-language-sample]
=====
.build.gradle.kts
[source,kotlin]