See attached example. Consider the schema for param0, which has type=string and format=date-time.
Because of this format, an instance of DateTimeSchema is created. Then to handle the "enum" array, OpenAPIDeserializer.getSchema() iterates over each TextNode in the array, calling DateTimeSchema.addEnumItemObject() with the corresponding String value. This invokes DateTimeSchema.cast(), which should decode the String as an RFC3339 date-time.
But it doesn't. Instead, since a String is not a Date, it just substitutes null. Yikes!
The same problem occurs with other string formats that required decoding, specifically "byte" and "date".
string-8.json.txt