Add license header to each groovy file in a folder using a groovy script

add license header.groovy

import static groovy.io.FileType.*
import static groovy.io.FileVisitResult.*
def headerFile = new File("/home/markus/Projects/olf_gpl3_license.txt")
def headerLines = headerFile.readLines()
def sourcebase = new File("/home/markus/Projects/OpenLabFramework")
sourcebase.traverse(
    type       : FILES,
    nameFilter : ~/.*\.groovy/,
    preDir     : { if (it.name == '.svn' || it.name == '.idea' || it.name == '.git') return SKIP_SUBTREE }
) { f ->
    def lines = f.readLines()
    if (lines.size() < headerLines.size()) println "$f.name rejected: insufficient size"
    for (int i in 0..<headerLines.size()) {
        if (!(lines[i] ==~ headerLines[i])) {
            println "Mismatch at line ${i+1} of $f.canonicalPath\n  expect:${headerLines[i]}\n  actual:${lines[i]}"
            println "Adding file header..."
            f.text = headerFile.text + f.text
            return
        }
    }
    
}