(Map)

Forces (casts/coerces) the configuration to be treated as a map even if the map has a single entry, which by default is treated as object definition <type>: <configuration>.

The below specification will not load because json map has a single entry name: icon.gif. Because the map has a single entry it is treated as an object definition with name type and icon.gif configuration.

json:
    name: icon.gif                

This specification addresses the problem when a map with a single entry is required. It uses (map) type which treats its configuration as a map even if it has a single entry.

json:
    (map):
        name: icon.gif