@Override
        public String toString() {
            return value;
        }
Create a {@code Format} from a string that would appear in a model.

<p>Any unknown value is returned as {@code Unknown}.

@param value Value from a trait or model.
@return Returns the Format enum value.
smithy-model/src/main/java/software/amazon/smithy/model/traits/TimestampFormatTrait.java