Create a ZIP/JAR file in Groovy

script.groovy

/**
 * Create a ZIP/JAR file with given contents.
 *
 * @param destination destination file
 * @param contents map of filename and content
 */
void createZIP(File destination, Map<String, String> contents) {
    destination.withOutputStream {
        new ZipOutputStream(it).withStream { zip ->
            contents.each { filename, content ->
                zip.putNextEntry(new ZipEntry(filename))
                zip << content
                zip.closeEntry()
            }
        }
    }
}