fields property
The document's fields.
The map keys represent field names. Field names matching the regular
expression __.*__ are reserved. Reserved field names are forbidden
except in certain documented contexts. The field names, 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 a dot-delimited (.) string
of segments. Each segment is either a simple field name (defined below) or
a quoted field name. For example, the structured field "foo" : { map_value: { "x&y" : { string_value: "hello" }}} would be represented by
the field path foo.`x&y`. 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. 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;