added support for c-style hex numbers to be exported as strings

Author: hoonality

src/Microsoft.OpenApi/Writers/SpecialCharacterStringExtensions.cs

@@ -187,9 +187,10 @@ internal static string GetYamlCompatibleString(this string input)
                 return $"'{input}'";
             }
 
-            // If string can be mistaken as a number, a boolean, or a timestamp,
-            // wrap it in quote to indicate that this is indeed a string, not a number, a boolean, or a timestamp
+            // If string can be mistaken as a number, c-style hexadecimal notation, a boolean, or a timestamp,
+            // wrap it in quote to indicate that this is indeed a string, not a number, c-style hexadecimal notation, a boolean, or a timestamp
             if (decimal.TryParse(input, NumberStyles.Float, CultureInfo.InvariantCulture, out var _) ||
+                IsHexadecimalNotation(input) ||
                 bool.TryParse(input, out var _) ||
                 DateTime.TryParse(input, out var _))
             {
@@ -225,5 +226,10 @@ internal static string GetJsonCompatibleString(this string value)
 
             return $"\"{value}\"";
         }
+
+        internal static bool IsHexadecimalNotation(string input)
+        {
+            return input.StartsWith("0x") && int.TryParse(input.Substring(2), NumberStyles.HexNumber, CultureInfo.InvariantCulture, out var _);
+        }
     }
 }