fix: add empty value check in getRequestBodyExamples() (#904)

| 🚥 Resolves ISSUE_ID |
| :------------------- |

## 🧰 Changes
There is a weird case in our main repo where we initialize `Webhooks`
with an empty `requestBodyExamples` with the following structure:
```
requestBodyExamples: [
  {
    mediaType: 'application/json',
    examples: [{
      value: undefined
    }],
  },
];
```

This causes `Operation.getRequestBodyExamples()` to return with an empty
request example even though we should be creating an example for them.
This adds an extra check so that we avoid returning the empty example
and proceed to the subsequent `getRequestBodyExamples()` call that
generates an example for the user.

## 🧬 QA & Testing

Provide as much information as you can on how to test what you've done.

packages/oas/src/operation/index.ts

@@ -708,7 +708,9 @@ export class Operation {
    *
    */
   getRequestBodyExamples(): RequestBodyExamples {
-    if (this.requestBodyExamples) {
+    const isRequestExampleValueDefined = typeof this.requestBodyExamples?.[0]?.examples?.[0].value !== 'undefined';
+
+    if (this.requestBodyExamples && isRequestExampleValueDefined) {
       return this.requestBodyExamples;
     }
 

packages/oas/test/operation/lib/get-requestbody-examples.test.ts

@@ -5,20 +5,54 @@ import cleanStringify from '../../__fixtures__/json-stringify-clean.js';
 
 let operationExamples: Oas;
 let petstore: Oas;
+let webhooksOas: Oas;
 
 beforeAll(async () => {
   operationExamples = await import('../../__datasets__/operation-examples.json').then(r => r.default).then(Oas.init);
   await operationExamples.dereference();
 
   petstore = await import('@readme/oas-examples/3.0/json/petstore.json').then(r => r.default).then(Oas.init);
   await petstore.dereference();
+
+  webhooksOas = await import('@readme/oas-examples/3.1/json/webhooks.json').then(r => r.default).then(Oas.init);
 });
 
 test('should return early if there is no request body', () => {
   const operation = operationExamples.operation('/nothing', 'get');
   expect(operation.getRequestBodyExamples()).toStrictEqual([]);
 });
 
+test('should re-intialize the request examples after the oas is dereferenced', async () => {
+  const webhookOperation = webhooksOas.operation('newPet', 'post', { isWebhook: true });
+
+  expect(webhookOperation.getRequestBodyExamples()).toStrictEqual([
+    {
+      mediaType: 'application/json',
+      examples: [
+        {
+          value: undefined,
+        },
+      ],
+    },
+  ]);
+
+  await webhooksOas.dereference();
+  expect(webhookOperation.getRequestBodyExamples()).toStrictEqual([
+    {
+      mediaType: 'application/json',
+      examples: [
+        {
+          value: {
+            id: 0,
+            name: 'string',
+            tag: 'string',
+          },
+        },
+      ],
+    },
+  ]);
+});
+
 test('should support */* media types', () => {
   const operation = operationExamples.operation('/wildcard-media-type', 'post');
   expect(operation.getRequestBodyExamples()).toStrictEqual([