When reading in a _very simple _ nested yaml, readYaml does not convert it to a nested map, but to a flat map.

The following snippet gives

def myYaml = "aim.setup: true"
yamlMap = readYaml(text: myYaml)

a map with key 

aim.setup

(not a map aim -> map: setup: true.

With more complex yamls, I don't face the problem.