All examples that are a composite type (array, object) should be quoted, to avoid YAML interpreting them

[webmat]

This issue mostly affects objects (like the example for labels). But it could also affect arrays, if for example we have an array that contains an unquoted NO, which would be interpreted by YAML as False, rather than the string "NO".

This issue not only affects the generated artifacts in the ECS repo, but also artifacts down the line, e.g. Beats starting from generated/beats/fields.ecs.yml and in turn generating various other artifacts.

• Quote the labels example, to avoid the YAML interpreter interpreting it #782 Immediate need is to fix labels to double quote it, an each values inside, to fix an issue in Beats
• Add example value composite type checking #966 Fix all of the arrays
• Add example value composite type checking #966 Add a linting rule or fail the build if any example: contains directly an array or an object, rather than a scalar.

[codebrain]

++ this would also help the .NET client where I have had to handle examples by "santizing" them so they can be safely written into XML comments:

https://github.com/elastic/ecs-dotnet/blob/dc0d44fe1b0b3028a6a1cec044c7d8b30d4423a7/src/Generator/SchemaExtensionMethods.cs#L18-L23

[gen0cide]

This definitely has created issues with trying to parse ECS YAML (both the source schema, as well as the generated).

Basically, the field has to get specified as:

type Definition struct {
  // ... other fields
  Example          interface{}     `config:"example"`
}

So normalizing this certainly removes that ugly workaround. Thanks!