private String createInvalidHttpDateMessage(String dateValue) {
        return String.format(
                "Invalid value provided for %s formatted timestamp. Expected a string value that "
                        + "matches the IMF-fixdate production of RFC 9110 section-5.6.7. Found: %s",
                TimestampFormatTrait.HTTP_DATE,
                dateValue);
    }
Validates that timestamp shapes contain values that are compatible with their
timestampFormat traits or contain values that are numbers or an RFC 3339
date-time production.
smithy-model/src/main/java/software/amazon/smithy/model/validation/node/TimestampFormatPlugin.java