Understand unstructured

setNestedFieldNoCopy

https://github.com/kubernetes/apimachinery/blob/master/pkg/apis/meta/v1/unstructured/helpers.go#L212:6

func setNestedFieldNoCopy(obj map[string]interface{}, value interface{}, fields ...string) error {
	m := obj

	for i, field := range fields[:len(fields)-1] {
		if val, ok := m[field]; ok {
			if valMap, ok := val.(map[string]interface{}); ok {
				m = valMap
			} else {
				return fmt.Errorf("value cannot be set because %v is not a map[string]interface{}", jsonPath(fields[:i+1]))
			}
		} else {
			newVal := make(map[string]interface{})
			m[field] = newVal
			m = newVal
		}
	}
	m[fields[len(fields)-1]] = value
	return nil
}