双引号字符串（插值）

def param = 'string'
def str = "Double quoted ${param}"
assert str instanceof GString
assert str == 'Double quoted string'

默认情况下，该参数是急切解决的，这意味着这适用：

def param = 'string'
def str = "Double quoted ${param}"
param = 'another string'
assert str == 'Double quoted string'

为了在每次使用字符串时懒惰地加载参数，可以这样做：

def param = 'string'
def str = "Double quoted ${ -> param}"
assert str == 'Double quoted string'
param = 'lazy load'
assert str == 'Double quoted lazy load'