Your code works fine.
def list = [["c":"d"], ["e":"f"], ["g":"h"]]
Map tmpHM = [1:"second (e:f)", 0:"first (c:d)", 2:"third (g:h)"]
for (objKey in tmpHM.keySet()) {
HashMap objHM = (HashMap) list.get(objKey);
print("objHM: ${objHM} , ")
}
prints objHM: [e:f] , objHM: [c:d] , objHM: [g:h] ,
See https://groovyconsole.appspot.com/script/5135817529884672
Then click "edit in console", "execute script"