validation failing when describing request body for post request using "style" and "explode" serialization strategy

When describing the request body for a post request using "style" and "explode" as serialization strategy for primitive types rather than defining "contentType" (used for more complex serialization strategies), the validation is failing.

Relative documentation is https://swagger.io/docs/specification/describing-request-body/ in the "Form Data" and "Complex Serialization in Form Data" sections.

The API I'm trying to validate is here: https://raw.githubusercontent.com/BibleGet-I-O/endpoint/master/openapi.json

I have defined it using swaggerhub, where it shows as being valid: https://app.swaggerhub.com/apis/JohnRDOrazio/BibleGet/2.8

If instead I try validating with the badge validator: https://validator.swagger.io/validator/debug?url=https://raw.githubusercontent.com/BibleGet-I-O/endpoint/master/openapi.json

I get these errors:

{"messages":["attribute paths.'/index.php'(post).requestBody.content.encoding.contentType is missing","attribute paths.'/metadata.php'(post).requestBody.content.encoding.contentType is missing"],"schemaValidationMessages":[{"level":"warning","domain":"validation","keyword":"format","message":"format attribute \"uri-reference\" not supported","schema":{"loadingURI":"#","pointer":"/definitions/Contact/properties/url"}},{"level":"warning","domain":"validation","keyword":"format","message":"format attribute \"uri-reference\" not supported","schema":{"loadingURI":"#","pointer":"/definitions/License/properties/url"}},{"level":"warning","domain":"validation","keyword":"format","message":"format attribute \"uri-reference\" not supported","schema":{"loadingURI":"#","pointer":"/definitions/Info/properties/termsOfService"}}]}

Reproduce the failure using the supplied endpoint OpenAPI JSON and the validator debug URL, focusing on the requestBody encoding entries for the POST paths. Compare the validator's requirement for contentType with the OpenAPI form-data documentation and SwaggerHub result; done means the valid style/explode serialization no longer produces missing-contentType errors.