Guessing datetime offset type from empty string

Author: VitaliyKurokhtin

src/Microsoft.OpenApi.Readers/ParseNodes/OpenApiAnyConverter.cs

@@ -50,12 +50,24 @@ public static IOpenApiAny GetSpecificOpenApiAny(IOpenApiAny openApiAny, OpenApiS
                 return newObject;
             }
 
-            if (!(openApiAny is OpenApiString) || ((OpenApiString)openApiAny).IsExplicit())
+            if (!(openApiAny is OpenApiString))
             {
                 return openApiAny;
             }
 
             var value = ((OpenApiString)openApiAny).Value;
+
+            // For explicit strings only try to guess if it's a DateTimeOffset
+            if (((OpenApiString)openApiAny).IsExplicit())
+            {
+                if (DateTimeOffset.TryParse(value, CultureInfo.InvariantCulture, DateTimeStyles.None, out var dateTimeValue))
+                {
+                    return new OpenApiDateTime(dateTimeValue);
+                }
+
+                return openApiAny;
+            }
+
             if (value == null || value == "null")
             {
                 return new OpenApiNull();

test/Microsoft.OpenApi.Readers.Tests/V3Tests/Samples/OpenApiExample/explicitString.yaml

@@ -20,14 +20,17 @@ components:
       properties:
         sub:
           $ref: '#/components/schemas/test-sub-schema'
-      required:
-        - origin
       example:
         sub:
-          test-property: "12345"
+          test-property1: "12345"
+          test-property2: "1970-01-01T00:00:00Z"
     test-sub-schema:
       type: object
       properties:
-        test-property:
+        test-property1:
           type: string
-          example: "12345"
+          example: "12345"
+        test-property2:
+          type: string
+          format: date-time
+          example: "1970-01-01T00:00:00Z"