Limited requestBody content types supported

given the following section of a swagger file:
```yml
requestBody:
description: InfluxQL query to execute.
content:
application/vnd.influxql:
schema:
type: string
```
I get the following error when generating a client:
```
(node:67136) UnhandledPromiseRejectionWarning: TypeError: Cannot read property '0' of undefined
at Generator.collectBodyParam (/go/src/github.com/influxdata/influxdb/ui/node_modules/@influxdata/oats/dist/generate.js:91:65)
at Generator.registerPathOperation (/go/src/github.com/influxdata/influxdb/ui/node_modules/@influxdata/oats/dist/generate.js:40:29)
at new Generator (/go/src/github.com/influxdata/influxdb/ui/node_modules/@influxdata/oats/dist/generate.js:24:26)
at generate (/go/src/github.com/influxdata/influxdb/ui/node_modules/@influxdata/oats/dist/generate.js:219:23)
at async Command. (/go/src/github.com/influxdata/influxdb/ui/node_modules/@influxdata/oats/bin/oats:7:18)
(node:67136) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:67136) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
```

lines 89-92 of `generate.js` are as follows:
```js
const fallbackEntry = mediaTypeEntries[0];
if (fallbackEntry) {
return { description, required, mediaType: textEntry[0], type: "any" };
}
```

The resolution was to change the content from `application/vnd.influxql` to `text/plain` and add a header parameter
```yml
- in: header
name: Content-Type
schema:
type: string
enum:
- application/vnd.influxql
```

Start with generate.js lines 89-92 in collectBodyParam and reproduce generation using the shown application/vnd.influxql requestBody schema. Compare the failure with the text/plain and Content-Type header workaround. Done means the custom media type no longer produces the reported TypeError and the generator behavior is verified.

Written by the indexing model from the issue text.