Addressed review comments

Author: pmathew92

EXAMPLES.md

@@ -215,7 +215,7 @@ WebAuthProvider.login(account)
 > [!NOTE]  
 > This feature is currently available in [Early Access](https://auth0.com/docs/troubleshoot/product-lifecycle/product-release-stages#early-access). Please reach out to Auth0 support to get it enabled for your tenant.
 
-[DPoP](https://www.rfc-editor.org/rfc/rfc9449.html) (Demonstrating Proof of Posession) is an application-level mechanism for sender-constraining OAuth 2.0 access and refresh tokens by proving that the app is in possession of a certain private key. You can enable it by calling the `useDPoP(context:Context)` method.
+[DPoP](https://www.rfc-editor.org/rfc/rfc9449.html) (Demonstrating Proof of Possession) is an application-level mechanism for sender-constraining OAuth 2.0 access and refresh tokens by proving that the app is in possession of a certain private key. You can enable it by calling the `useDPoP(context:Context)` method.
 
 ```kotlin
 WebAuthProvider
@@ -252,7 +252,7 @@ httpRequest.apply{
     }
 }
 ```
-If your API is issuing DPoP nonce's to prevent replay attacks, you can pass the nonce value to the `getHeaderData()` method to include it in the DPoP proof. Use the `DPoPProvider.isNonceRequiredError(response: Response)` method to check if a particular API response failed because a nonce is required.
+If your API is issuing DPoP nonces to prevent replay attacks, you can pass the nonce value to the `getHeaderData()` method to include it in the DPoP proof. Use the `DPoPProvider.isNonceRequiredError(response: Response)` method to check if a particular API response failed because a nonce is required.
 
 ```kotlin
 if (DPoPProvider.isNonceRequiredError(response)) {
@@ -755,7 +755,7 @@ httpRequest.apply{
     }
 }
 ```
-If your API is issuing DPoP nonce's to prevent replay attacks, you can pass the nonce value to the `getHeaderData()` method to include it in the DPoP proof. Use the `DPoPProvider.isNonceRequiredError(response: Response)` method to check if a particular API response failed because a nonce is required.
+If your API is issuing DPoP nonces to prevent replay attacks, you can pass the nonce value to the `getHeaderData()` method to include it in the DPoP proof. Use the `DPoPProvider.isNonceRequiredError(response: Response)` method to check if a particular API response failed because a nonce is required.
 
 ```kotlin
 if (DPoPProvider.isNonceRequiredError(response)) {

auth0/src/main/java/com/auth0/android/dpop/DPoPProvider.kt

@@ -118,7 +118,7 @@ public object DPoPProvider {
     }
 
     /**
-     * Method to clear the DPoP key pair from the keystore. It must be called when the user logs out from a session
+     * Method to clear the DPoP key pair from the keystore. It must be called when the user logs out
      * to prevent reuse of the key pair in subsequent sessions.
      *
      * ```kotlin
@@ -130,7 +130,7 @@ public object DPoPProvider {
      *     }
      *
      * ```
-     * **Note** : It is the developers responsibility to invoke this method to clear the keystore when logging out  a session.
+     * **Note** : It is the developer's responsibility to invoke this method to clear the keystore when logging out .
      * @throws DPoPException if there is an error deleting the key pair.
      */
     @Throws(DPoPException::class)
@@ -175,7 +175,7 @@ public object DPoPProvider {
     }
 
     /**
-     * Generates a new key pair for DPoP if it does not already exist. This should be called before making any requests that require DPoP proof.
+     * Generates a new key pair for DPoP if it does not already exist. This should be called before making any requests that require a DPoP proof.
      *
      * ```kotlin
      *
@@ -201,7 +201,7 @@ public object DPoPProvider {
 
     /**
      * Generates the header data for a request that requires DPoP proof of possession. The `Authorization` header value is created
-     * using the access token and token type. The `DPoP` header value contains the generated DPoP proof
+     * using the access token and token type. The `DPoP` header value contains the generated DPoP proof.
      *
      * ```kotlin
      *

auth0/src/main/java/com/auth0/android/request/RetryInterceptor.kt

@@ -16,22 +16,24 @@ internal class RetryInterceptor : Interceptor {
 
         //Handling DPoP Nonce retry
         if (DPoPProvider.isNonceRequiredError(response) && currentRetryCount < DPoPProvider.MAX_RETRY_COUNT) {
-            DPoPProvider.storeNonce(response)
-            val accessToken =
-                request.headers[AUTHORIZATION_HEADER]?.substringAfter(DPOP_LIMITER)?.trim()
-            val dpopProof = DPoPProvider.generateProof(
-                httpUrl = request.url.toString(),
-                httpMethod = request.method,
-                accessToken = accessToken,
-                nonce = DPoPProvider.auth0Nonce
-            )
-            if (dpopProof != null) {
-                response.close()
-                val newRequest = request.newBuilder()
-                    .header(DPoPProvider.DPOP_HEADER, dpopProof)
-                    .header(RETRY_COUNT_HEADER, (currentRetryCount + 1).toString())
-                    .build()
-                return chain.proceed(newRequest)
+            synchronized(this) {
+                DPoPProvider.storeNonce(response)
+                val accessToken =
+                    request.headers[AUTHORIZATION_HEADER]?.substringAfter(DPOP_LIMITER)?.trim()
+                val dpopProof = DPoPProvider.generateProof(
+                    httpUrl = request.url.toString(),
+                    httpMethod = request.method,
+                    accessToken = accessToken,
+                    nonce = DPoPProvider.auth0Nonce
+                )
+                if (dpopProof != null) {
+                    response.close()
+                    val newRequest = request.newBuilder()
+                        .header(DPoPProvider.DPOP_HEADER, dpopProof)
+                        .header(RETRY_COUNT_HEADER, (currentRetryCount + 1).toString())
+                        .build()
+                    return chain.proceed(newRequest)
+                }
             }
         }
         return response

auth0/src/test/java/com/auth0/android/provider/WebAuthProviderTest.kt

@@ -322,7 +322,7 @@ public class WebAuthProviderTest {
     //jwk
 
     @Test
-    public fun enablingDPoPWillGenerateNEwKEyPairIfOneDoesNotExist() {
+    public fun enablingDPoPWillGenerateNewKeyPairIfOneDoesNotExist() {
         `when`(mockKeyStore.hasKeyPair()).thenReturn(false)
         val context: Context = mock()
         WebAuthProvider.useDPoP(context)
@@ -348,7 +348,7 @@ public class WebAuthProviderTest {
     }
 
     @Test
-    public fun shouldNotHaveDpopJwkOnLoginIfDPoPIsEnabled() {
+    public fun shouldHaveDpopJwkOnLoginIfDPoPIsEnabled() {
         `when`(mockKeyStore.hasKeyPair()).thenReturn(true)
         `when`(mockKeyStore.getKeyPair()).thenReturn(Pair(mock(), FakeECPublicKey()))
 

auth0/src/test/java/com/auth0/android/request/DefaultClientTest.kt

@@ -83,7 +83,7 @@ public class DefaultClientTest {
     @Test
     public fun shouldHaveLoggingDisabledByDefault() {
         val netClient = DefaultClient(enableLogging = false)
-        assertThat(DefaultClient().okHttpClient.interceptors, hasSize(1))
+        assertThat(netClient.okHttpClient.interceptors, hasSize(1))
         val interceptor: Interceptor = netClient.okHttpClient.interceptors[0]
         assert(
             interceptor is RetryInterceptor,
@@ -92,7 +92,12 @@ public class DefaultClientTest {
 
     @Test
     public fun shouldHaveRetryInterceptorEnabled() {
-        assertThat(DefaultClient().okHttpClient.interceptors, hasSize(1))
+        val netClient = DefaultClient(enableLogging = false)
+        assertThat(netClient.okHttpClient.interceptors, hasSize(1))
+        val interceptor: Interceptor = netClient.okHttpClient.interceptors[0]
+        assert(
+            interceptor is RetryInterceptor,
+        )
     }
 
     @Test