Fatal Exception: java.lang.NullPointerException: Parameter specified as non-null is null

The user is facing a crash. Here are crash logs from the firebase which address to AppSync classes.

```
Fatal Exception: java.lang.NullPointerException: Parameter specified as non-null is null: method k.d0$a.a, parameter value
at okhttp3.Request$Builder.a(Request.kt:7)
atcom.amazonaws.mobileconnectors.appsync.sigv4.AppSyncSigV4SignerInterceptor.intercept(AppSyncSigV4SignerInterceptor.java:189)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
at com.amazonaws.mobileconnectors.appsync.retry.RetryInterceptor.intercept(RetryInterceptor.java:40)
at okhttp3.internal.http.RealInterceptorChain.proceed(RealInterceptorChain.kt:109)
at okhttp3.internal.connection.RealCall.getResponseWithInterceptorChain$okhttp(RealCall.kt:201)
at okhttp3.internal.connection.RealCall$AsyncCall.run(RealCall.kt:517)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
at java.lang.Thread.run(Thread.java:923)
```

**Environment:**
- AppSync SDK Version: 3.2.0

**Device Information:**
- Device: ZTE Z6356T
- Android Version: 11
- Specific to simulators: No

**Additional context**
The user has an internet connection.

Start at AppSyncSigV4SignerInterceptor.java:189 and trace the request construction into okhttp3.Request.Builder, using the supplied stack trace and SDK version 3.2.0. Reproduce the crash on Android 11 if possible, then verify that the reported null-parameter exception no longer occurs.

Written by the indexing model from the issue text.