surprise when using string variable/constant as Map's key

Sandbox.groovy

// Illustration of a side effect when using string variable/constant for map's key


def PROP_NAME = "property name"

def myMap = [PROP_NAME: "a Value"]

//assert myMap.keySet().iterator().next() == "property name"
// fails at runtime but it compiles.
// I was expecting the value of the variable to be the key, but it is in fact a String with the name of the variable
assert myMap.keySet().iterator().next() == "PROP_NAME"


// working way: put the variable/constant in parentheses to have expected behavior
myMap = [(PROP_NAME): "a Value"]
assert myMap.keySet().iterator().next() == "property name"


// Second example with ENUM instead of variable/constant
enum MY_ENUM{
    ENUM_ONE, ENUM_TWO
}


//myMap = [MY_ENUM.ENUM_ONE: "blabla"]
// fails at compilation
// error message:
//Groovyc: illegal colon after argument expression;
//solution: a complex label expression before a colon must be parenthesized

//good way, add parentheses
myMap = [(MY_ENUM.ENUM_ONE): "blabla"]

assert myMap.keySet().iterator().next() == MY_ENUM.ENUM_ONE

A bit surprised by this behavior, but the parentheses seems to do the trick!