Fix refresh logic for App Check custom providers. (#3582)

* Fix refresh logic for App Check custom providers.

* Update tests.

* Extract 1000L into a constant.

Author: rosalyntan

appcheck/firebase-appcheck/src/main/java/com/google/firebase/appcheck/internal/DefaultAppCheckToken.java

@@ -41,6 +41,8 @@ public final class DefaultAppCheckToken extends AppCheckToken {
   @VisibleForTesting static final String ISSUED_AT_KEY = "iat";
   @VisibleForTesting static final String EXPIRATION_TIME_KEY = "exp";
 
+  private static final long ONE_SECOND_MILLIS = 1000L;
+
   // Raw token value
   private final String token;
   // Timestamp in MS at which this token was generated
@@ -79,7 +81,7 @@ public static DefaultAppCheckToken constructFromAppCheckTokenResponse(
           TokenParser.parseTokenClaims(tokenResponse.getAttestationToken());
       long iat = getLongFromClaimsSafely(claimsMap, ISSUED_AT_KEY);
       long exp = getLongFromClaimsSafely(claimsMap, EXPIRATION_TIME_KEY);
-      expiresInMillis = exp - iat;
+      expiresInMillis = (exp - iat) * ONE_SECOND_MILLIS;
     }
 
     return new DefaultAppCheckToken(tokenResponse.getAttestationToken(), expiresInMillis);
@@ -138,10 +140,10 @@ public static DefaultAppCheckToken constructFromRawToken(@NonNull String token)
     Map<String, Object> claimsMap = TokenParser.parseTokenClaims(token);
     long iat = getLongFromClaimsSafely(claimsMap, ISSUED_AT_KEY);
     long exp = getLongFromClaimsSafely(claimsMap, EXPIRATION_TIME_KEY);
-    long expiresInMillis = exp - iat;
+    long expiresInMillis = (exp - iat) * ONE_SECOND_MILLIS;
     // We use iat for receivedAtTimestamp as an approximation since we have to guess for raw JWTs
     // that we recovered from storage
-    return new DefaultAppCheckToken(token, expiresInMillis, iat);
+    return new DefaultAppCheckToken(token, expiresInMillis, iat * ONE_SECOND_MILLIS);
   }
 
   private static long getLongFromClaimsSafely(

appcheck/firebase-appcheck/src/test/java/com/google/firebase/appcheck/internal/DefaultAppCheckTokenTest.java

@@ -37,6 +37,7 @@ public class DefaultAppCheckTokenTest {
   private static final String INVALID_TIME_TO_LIVE = "notanumber";
   private static final long EXPIRES_IN_ONE_HOUR = 60L * 60L * 1000L; // 1 hour in millis
   private static final long RECEIVED_AT_TIMESTAMP = 1L;
+  private static final long ONE_SECOND_MILLIS = 1000L;
   private static final long IAT = 10L;
   private static final long EXP = 30L;
   private static final String TOKEN_PREFIX = "prefix";
@@ -104,8 +105,9 @@ public void testConstructFromRawToken_normalToken_expectSuccess() throws Excepti
 
     assertThat(defaultAppCheckToken).isNotNull();
     assertThat(defaultAppCheckToken.getToken()).isEqualTo(rawToken);
-    assertThat(defaultAppCheckToken.getReceivedAtTimestamp()).isEqualTo(IAT);
-    assertThat(defaultAppCheckToken.getExpiresInMillis()).isEqualTo(EXP - IAT);
+    assertThat(defaultAppCheckToken.getReceivedAtTimestamp()).isEqualTo(IAT * ONE_SECOND_MILLIS);
+    assertThat(defaultAppCheckToken.getExpiresInMillis())
+        .isEqualTo((EXP - IAT) * ONE_SECOND_MILLIS);
   }
 
   @Test
@@ -143,7 +145,8 @@ public void testConstructFromAppCheckTokenResponse_invalidTimeToLiveFormat_fallb
         DefaultAppCheckToken.constructFromAppCheckTokenResponse(mockAppCheckTokenResponse);
 
     assertThat(defaultAppCheckToken.getToken()).isEqualTo(rawToken);
-    assertThat(defaultAppCheckToken.getExpiresInMillis()).isEqualTo(EXP - IAT);
+    assertThat(defaultAppCheckToken.getExpiresInMillis())
+        .isEqualTo((EXP - IAT) * ONE_SECOND_MILLIS);
   }
 
   private String constructFakeRawToken() throws Exception {

appcheck/firebase-appcheck/src/test/java/com/google/firebase/appcheck/internal/StorageHelperTest.java

@@ -40,6 +40,7 @@ public class StorageHelperTest {
   private static final long RECEIVED_AT_TIMESTAMP = 10L;
   private static final long IAT = 10L;
   private static final long EXP = 30L;
+  private static final long ONE_SECOND_MILLIS = 1000L;
   private static final String TOKEN_PREFIX = "prefix";
   private static final String TOKEN_SUFFIX = "suffix";
   private static final String SEPARATOR = ".";
@@ -108,8 +109,8 @@ public void testSaveAndRetrieveToken_TestAppCheckToken_expectEquivalentToken() t
         (DefaultAppCheckToken) storageHelper.retrieveAppCheckToken();
     assertThat(retrievedToken).isNotNull();
     assertThat(retrievedToken.getToken()).isEqualTo(rawToken);
-    assertThat(retrievedToken.getExpiresInMillis()).isEqualTo(EXP - IAT);
-    assertThat(retrievedToken.getReceivedAtTimestamp()).isEqualTo(IAT);
+    assertThat(retrievedToken.getExpiresInMillis()).isEqualTo((EXP - IAT) * ONE_SECOND_MILLIS);
+    assertThat(retrievedToken.getReceivedAtTimestamp()).isEqualTo(IAT * ONE_SECOND_MILLIS);
   }
 
   @Test