You can convert a list to a map by using toSpreadMap(), convenient at times when the order in the list is enough to determine the keys and the values associated with them. See example below.
def list = ['key', 'value', 'foo', 'bar'] as Object[]
def map = list.toSpreadMap()
assert 2 == map.size()
assert 'value' == map.key
assert 'bar' == map['foo']
