com.google.firebase.auth.UserRecord.CreateRequest doesn't override .equals making it hard to test

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#### Relevant Code:

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I built an application with a function that call `firebaseAuth.createUserAsync(CreateRequest request)`. To test the logic in this function, I created a unit test for it with a mock:
```java
CreateRequest createRequest = // creates some request
UserRecord userRecord = // build a record

FirebaseAuth auth = mock(FirebaseAuth.class);
when(auth.createUserAsync(createRequest)).thenReturn(ApiFutures.immediateFuture(userRecord))
```
but when I ran the test I got a Null Pointer Exception from Mockito. On further inspection, I realized that two instances of CreateRequest with the same payload value return `false` when compared via `.equals`. This leads Mockito to think the function is not defined for this argument.

I am happy to contribute this simple (probably IntelliJ-generated) code, is there a reason you don't want this in there?

Start by locating com.google.firebase.auth.UserRecord.CreateRequest and the createUserAsync(CreateRequest request) entry point. Review the existing authentication tests, then verify that two requests with the same payload compare as expected and that the Mockito-based test no longer receives a null result.

Written by the indexing model from the issue text.