fields property
The document's fields.
The map keys represent field names. A simple field name contains only
characters a to z, A to Z, 0 to 9, or _, and must not start
with 0 to 9. For example, foo_bar_17. Field names matching the
regular expression __.*__ are reserved. Reserved field names are
forbidden except in certain documented contexts. The map keys, represented
as UTF-8, must not exceed 1,500 bytes and cannot be empty. Field paths may
be used in other contexts to refer to structured fields defined here. For
map_value, the field path is represented by the simple or quoted field
names of the containing fields, delimited by .. For example, the
structured field "foo" : { map_value: { "x&y" : { string_value: "hello" }}} would be represented by the field path foo.x&y. Within a field
path, a quoted field name starts and ends with ` and may contain any
character. Some characters, including `, must be escaped using a
\. For example, `x&y` represents x&y and `bak\`tik`
represents bak`tik.
Implementation
core.Map<core.String, Value>? fields;