What is the problem you're trying to solve
Was trying to get the following to work:

// DefaultConfig returns default configurations of cri plugin.
func DefaultConfig() PluginConfig {
	opts := `
[plugins."io.containerd.grpc.v1.cri".containerd.runtimes]
  [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc]
    runtime_type = "io.containerd.runc.v2"
    runtime_engine = ""
    runtime_root = ""
    privileged_without_host_devices = false
    base_runtime_spec = ""
    [plugins."io.containerd.grpc.v1.cri".containerd.runtimes.runc.options]
      BinaryName = "runc"
`
	var runcRuntimeDefault Runtime
	m, err := toml.Decode(opts, &runcRuntimeDefault)
	if err != nil {
		panic(fmt.Sprintf("toml decode error %v %v", m, err))
	}

when I ran containerd config default I discovered that the toml code we are using can't encode what it decodes when wrt toml.Primitive (the type we use for said ^ options).. a quick search I found:
BurntSushi/toml#189 (minor note: I tried the PR and it didn't fix my problem more investigation required)

Then I discovered that the last merged PR in https://github.com/BurntSushi/toml/pulls?q=is%3Apr+is%3Aclosed
that was non license related, was June of 2017.

Mostly the license change consisted of this diff: BurntSushi/toml@4678bf2#diff-7116ef0705885343c9e1b2171a06be0e

Describe the solution you'd like
Discussion regarding what we'd like to do for config going forward.
A) host our own toml project
B) review consider moving to a different toml project, e.g. Pelletier appears to be supported... https://github.com/pelletier/go-toml
C) replace our toml config with a different model entirely

1. json/yaml in conf files ... maybe use the CNI conf pattern