@Deprecated
        public Builder allowBoxedNull(boolean allowBoxedNull) {
            return allowOptionalNull(allowBoxedNull);
        }
Sets the strategy used to validate timestamps.

<p>By default, timestamps are validated using
{@link TimestampValidationStrategy#FORMAT}.

@param timestampValidationStrategy Timestamp validation strategy.
@return Returns the builder.
smithy-model/src/main/java/software/amazon/smithy/model/validation/NodeValidationVisitor.java