usethiserror::Error;/// Errors produced while parsing or validating field masks.
#[derive(Debug, Error, PartialEq, Eq)]pubenumFieldMaskError{/// The supplied field mask string has invalid syntax.
////// For example: empty segments (`"a..b"`), leading/trailing dots (`".a"` or `"a."`),
/// or an entirely empty mask when a non-empty one is required.
#[error("invalid field mask syntax")]
InvalidSyntax,/// The mask references an unknown path with respect to the `MaskSpec` schema.
////// The contained string is the full path that failed validation.
#[error("unknown field mask path: `{0}`")]
UnknownPath(String),}