// If the input is sparseHoles, then it will output sparseDatas and vice-versa.
// The input must have been already validated.
//
// This function mutates src and returns a normalized map where:
//   - adjacent fragments are coalesced together
//   - only the last fragment may be empty
//   - the endOffset of the last fragment is the total size
func invertSparseEntries(src []sparseEntry, size int64) []sparseEntry {
	dst := src[:0]