Groovy Logic Rule for format dd.mm.yyyy

def patient = context.getPatient(patientId)

def year = patient.getBirthdate().getYear() + 1900

def yearString = year + ""

def month = patient.getBirthdate().getMonth() + 1

def monthString

if(month < 10)
     monthString = "0" + month + ""
else
     monthString = month + ""

def day = patient.getBirthdate().getDay()
def dayString

if(day < 10)
     dayString = "0"+ day + "";

else
   dayString = day + ""

def res = dayString + "." + monthString + "." + yearString

return new Result(res)