Groovy function to convert a Salesforce id15 to id18

toSalesforceId18.groovy

def toSalesforceId18(String id) {
   // Converts a Salesforce id15 to id18.
   // Example:
   //    assert toSalesforceId18("001C000000o4Ooi") == "001C000000o4OoiIAE"
   // Details:
   //    https://blog.centerkey.com/2014/08/groovy-convert-salesforce-id15-id18.html
   // MIT License (c) 2019 Pilafian
   def valueToCode =     { ((it < 26 ? "A" : "0") as char) + it % 26 }
   def binaryToCode =    { valueToCode(Integer.parseInt(it, 2)) as char }
   def tripletToBinary = { it.reverse().replaceAll(/[^A-Z]/, "0").replaceAll(/[^0]/, "1") }
   def threeCodes =      { it.replaceAll(/(.....)/, { binaryToCode(tripletToBinary(it[0])) }) }
   return id?.size() == 15 ? id + threeCodes(id) : id
   }