PR fixes

Author: katcharov

driver-core/src/main/com/mongodb/MongoCredential.java

@@ -712,29 +712,33 @@ public static final class OidcCallbackResult {
 
         private final String accessToken;
 
-        @Nullable
         private final Duration expiresIn;
 
         @Nullable
         private final String refreshToken;
 
         /**
          * @param accessToken The OIDC access token.
-         * @param expiresIn Time until the access token expires. 0 is an infinite duration.
+         * @param expiresIn Time until the access token expires.
+         *                  A {@linkplain Duration#isZero() zero-length} duration
+         *                  means that the access token does not expire.
          */
         public OidcCallbackResult(final String accessToken, final Duration expiresIn) {
             this(accessToken, expiresIn, null);
         }
 
         /**
          * @param accessToken The OIDC access token.
-         * @param expiresIn Time until the access token expires. 0 is an infinite duration.
+         * @param expiresIn Time until the access token expires.
+         *                  A {@linkplain Duration#isZero() zero-length} duration
+         *                  means that the access token does not expire.
          * @param refreshToken The refresh token. If null, refresh will not be attempted.
          */
-        public OidcCallbackResult(final String accessToken, @Nullable final Duration expiresIn,
+        public OidcCallbackResult(final String accessToken, final Duration expiresIn,
                 @Nullable final String refreshToken) {
             notNull("accessToken", accessToken);
-            if (expiresIn != null && expiresIn.isNegative()) {
+            notNull("expiresIn", expiresIn);
+            if (expiresIn.isNegative()) {
                 throw new IllegalArgumentException("expiresIn must not be a negative value");
             }
             this.accessToken = accessToken;