How can I modify a Jenkins job environment variable value using Groovy? -

im using groovy postbuild plugin , trying modify exists job environment variable test im running on jobs log:

def map = ["x":"", "y":"", "z":""]  map.each{ it.value = (manager.getlogmatcher("$it.key(.*)\$")).tostring().split(':')[1] }  if(map.get('x') == ""){  job_environment_variable = foo } else {  job_environment_variable = boo }