FieldsV1 stores a set of fields in a data structure like a Trie, in JSON format.

Each key is either a '.' representing the field itself, and will always map to an empty set, or a string representing a sub-field or item. The string will follow one of these four formats: 'f:', where is the name of a field in a struct, or key in a map 'v:', where is the exact json formatted value of a list item 'i:', where is position of a item in a list 'k:', where is a map of a list item's key fields to their unique values If a key maps to an empty Fields value, the field that key represents is part of the set.

The exact format is defined in sigs.k8s.io/structured-merge-diff