builder.setClasspath(validClasspath.files.toTypedArray())

        val validSourcepath = sourcepath.filter { it.exists() }
        builder.setProperty("project.sourcepath", validSourcepath.asPath)
        builder.setSourcepath(validSourcepath.files.toTypedArray())

        val builtJar = builder.build()
        if (!builder.isOk) {
          builder.getErrors().forEach { task.logger.error("Error: $it") }