func (l *FieldList) Load(f []Field, _ *DocumentMetadata) error {
	*l = append(*l, f...)
	return nil
}
func (l *FieldList) Load(f []Field, _ *DocumentMetadata) error {
	*l = append(*l, f...)
	return nil
}
// Load loads all of the provided fields into l.
// It does not first reset *l to an empty slice.