private boolean isJson(MediaType mediaType) {
        return mediaType.getSubtype().equals("json") || mediaType.getSuffix().orElse("").equals("json");
    }
Validates the following:

<ul>
    <li>XML and JSON bodyMediaTypes contain valid content.</li>
    <li>vendorParamsShape is a valid shape.</li>
    <li>Vendor params are compatible with any referenced shape.</li>
    <li>Params for a test case are valid for the model.</li>
</ul>

@param <T> Type of test case to validate.
smithy-protocol-test-traits/src/main/java/software/amazon/smithy/protocoltests/traits/ProtocolTestCaseValidator.java