@type t() :: %Envoy.Config.Core.V3.SubstitutionFormatString{
__unknown_fields__: [
{field_number :: integer(), Protobuf.Wire.Types.wire_type(),
value :: term()}
],
content_type: String.t(),
format:
{:text_format, String.t()}
| {:json_format, Google.Protobuf.Struct.t() | nil}
| {:text_format_source, Envoy.Config.Core.V3.DataSource.t() | nil}
| nil,
formatters: [Envoy.Config.Core.V3.TypedExtensionConfig.t()],
json_format_options: Envoy.Config.Core.V3.JsonFormatOptions.t() | nil,
omit_empty_values: boolean()
}