code: func BuilderVersion(features map[string]bool) types.BuilderVersion {
  	var bv types.BuilderVersion
  	if v, ok := features["buildkit"]; ok {
  		if v {
  			bv = types.BuilderBuildKit
  		} else {
  			bv = types.BuilderV1
  		}
  	}
  	return bv
  }
docs: // BuilderVersion derives the default docker builder version from the config
  // Note: it is valid to have BuilderVersion unset which means it is up to the
  // client to choose which builder to use.