Boolean and integer values are not serialized correctly.

[GillesTourreau]

When using the following YAML:

object:
   boolValue: true
   integerValue: 1234

The following JSON content is generated and the boolean and integer values are considered as string:

{
  "object": {
    "boolValue": "true",
    "integerValue": "1234"
  }
}

[GillesTourreau]

After investigation this issue come from the YamlDotNet library issue : aaubry/YamlDotNet#289