欄位路徑可以使用 (backtick). The only character that needs
to be escaped within a quoted field path is the backtick character itself,
escaped using a backslash. Special characters in field paths that
must be quoted include:*,.,
``` (backtick),[,]` 和任何 ASCII 符號字元來引用。
例如:(注意:此處的註解是以 Markdown 語法編寫,因此使用另一層反引號來代表程式碼區塊) \address.city`represents a field namedaddress.city, not the map key
cityin the fieldaddress.
`*`represents a field named*`,不是任何欄位。
特殊的 Field 包含所有欄位的預設索引設定。這個欄位的資源名稱為:這個 Field 中定義的 projects/{projectId}/databases/{databaseId}/collectionGroups/__default__/fields/* 索引,會套用至所有沒有 Field 索引設定的欄位。