How to modify source code using task in build.gradle.kts?

Question

I have a script that can print when necessary line is found in generated source code, but I have to remove those lines as well, I am wondering how can I do that? This task seems to be working for groovy but only prints found values for Kotlin.

tasks.register<Copy>("filter") {
    from("src/generate-swagger/java") {
        filter { line ->
            if (line.contains("com.magazine.report.exception")) {
                println("found import")
                return@filter null
            }
            if (line.contains("throw new ReportException")) {
                println("found exception")
                return@filter line.replace("throw new ReportException", "throw new RuntimeException")
            }
            return@filter line
        }
    }
    into("generated/java")
    dependsOn("generate")
}

Answer 1

I was able to modify the content doing the following:

tasks.register<Copy>("filter") {
    from("src/generate-swagger/java") {
        filter { line ->
            if (line.contains("com.magazine.report.exception")) {
                return@filter ""
            }
            if (line.contains("throw new ReportException")) {
                return@filter line.replace("throw new ReportException", "throw new RuntimeException")
            }
            return@filter line
        }
    }
    into("generated/java")
    dependsOn("generate")
}