Subsettings should be indented (i.e. be children)

[Sophist-UK]

I tried to create a PR with the sub-settings indented (as I have successfully done several times in other situations) but the sub-settings fail to appear. I assume that this is some issue about how children are handled when the setting definitions json file is processed, but I am unable to determine where this is and so unable to fix it. (I have looked in the definition of the parent object and its not there either.)

I am attaching a copy of the indented settings file in case anyone else wants to try to make it work.

gradual_flow_settings.def.json