feat(tests): Add tests with offline_access scope in OAuth2AgentKeycloakIT

This change simply adds a few more tests to exercise the behavior of the agent against Keycloak, when offline tokens are requested.

Author: adutra

oauth2/core/src/intTest/java/com/dremio/iceberg/authmgr/oauth2/agent/OAuth2AgentKeycloakIT.java

@@ -56,6 +56,7 @@
 import com.nimbusds.jwt.JWTParser;
 import com.nimbusds.oauth2.sdk.ErrorObject;
 import com.nimbusds.oauth2.sdk.GrantType;
+import com.nimbusds.oauth2.sdk.Scope;
 import com.nimbusds.oauth2.sdk.auth.Secret;
 import com.nimbusds.oauth2.sdk.id.ClientID;
 import com.nimbusds.oauth2.sdk.pkce.CodeChallengeMethod;
@@ -284,8 +285,8 @@ void impersonation1(
   /**
    * Tests a simple impersonation scenario with the agent using its own token as the subject token,
    * and no actor token. The agent swaps its token for another one, roughly equivalent. Refresh
-   * tokens are present, which is why the client credentials grant cannot be used for the subject
-   * token.
+   * tokens are present, which is why the client credentials or jwt-bearer grant cannot be used for
+   * the subject token.
    */
   @CartesianTest
   void impersonation2(
@@ -508,17 +509,92 @@ void agentCopy(Builder envBuilder) throws Exception {
     }
   }
 
+  /**
+   * Tests that requesting the offline_access scope in interactive grants returns an offline refresh
+   * token (one that is not bound to the SSO session lifetime).
+   */
+  @CartesianTest
+  void offlineAccess(
+      @EnumLike(
+              excludes = {
+                "client_credentials",
+                "urn:ietf:params:oauth:grant-type:jwt-bearer",
+                "urn:ietf:params:oauth:grant-type:token-exchange"
+              })
+          GrantType grantType,
+      Builder envBuilder)
+      throws Exception {
+    try (TestEnvironment env =
+            envBuilder.grantType(grantType).scope(Scope.parse(SCOPE1 + " offline_access")).build();
+        OAuth2Agent agent = env.newAgent()) {
+      TokensResult tokens = agent.authenticateInternal();
+      JWT jwt = introspectToken(tokens.getTokens().getAccessToken(), CLIENT_ID1);
+      soft.assertThat(jwt.getJWTClaimsSet().getStringClaim("scope")).contains("offline_access");
+      soft.assertThat(tokens.getTokens().getRefreshToken()).isNotNull();
+      // Keycloak does not include an expiration time for
+      // refresh tokens with offline_access
+      soft.assertThat(tokens.getRefreshTokenExpirationTime()).isNull();
+    }
+  }
+
+  /**
+   * Tests token exchange where the subject token was obtained with offline_access scope. Requesting
+   * an access token should succeed, but requesting a refresh token should fail, as keycloak does
+   * not issue refresh tokens for offline sessions.
+   */
+  @CartesianTest
+  void offlineAccessImpersonation(
+      @EnumLike(
+              excludes = {
+                "client_credentials",
+                "urn:ietf:params:oauth:grant-type:jwt-bearer",
+                "urn:ietf:params:oauth:grant-type:token-exchange"
+              })
+          GrantType subjectGrantType,
+      Builder envBuilder)
+      throws Exception {
+    Scope offlineScope = Scope.parse(SCOPE1 + " offline_access");
+    try (TestEnvironment env =
+            envBuilder
+                .grantType(TOKEN_EXCHANGE)
+                .requestedTokenType(ACCESS_TOKEN)
+                .subjectGrantType(subjectGrantType)
+                .subjectScope(offlineScope)
+                .build();
+        OAuth2Agent agent = env.newAgent()) {
+      assertAgent(agent, CLIENT_ID1, false);
+    }
+    try (TestEnvironment env =
+            envBuilder
+                .grantType(TOKEN_EXCHANGE)
+                .requestedTokenType(REFRESH_TOKEN)
+                .subjectGrantType(subjectGrantType)
+                .subjectScope(offlineScope)
+                .build();
+        OAuth2Agent agent = env.newAgent()) {
+      soft.assertThatThrownBy(agent::authenticate)
+          .asInstanceOf(type(OAuth2Exception.class))
+          .extracting(OAuth2Exception::getErrorObject)
+          .extracting(ErrorObject::getHTTPStatusCode, ErrorObject::getCode)
+          .containsExactly(400, "invalid_request");
+    }
+  }
+
   private void assertAgent(OAuth2Agent agent, String clientId, boolean expectRefreshToken)
       throws Exception {
     // initial grant
     TokensResult initial = agent.authenticateInternal();
     introspectToken(initial.getTokens().getAccessToken(), clientId);
     // token refresh
     if (expectRefreshToken) {
+      // Refresh tokens without offline_access are bound by the user session;
+      // Keycloak returns the refresh token expiration time in these cases.
       soft.assertThat(initial.getTokens().getRefreshToken()).isNotNull();
+      soft.assertThat(initial.getRefreshTokenExpirationTime()).isNotNull();
       TokensResult refreshed = agent.refreshCurrentTokens(initial).toCompletableFuture().get();
       introspectToken(refreshed.getTokens().getAccessToken(), clientId);
       soft.assertThat(refreshed.getTokens().getRefreshToken()).isNotNull();
+      soft.assertThat(refreshed.getRefreshTokenExpirationTime()).isNotNull();
     } else {
       soft.assertThat(initial.getTokens().getRefreshToken()).isNull();
     }
@@ -527,16 +603,18 @@ private void assertAgent(OAuth2Agent agent, String clientId, boolean expectRefre
     introspectToken(renewed.getTokens().getAccessToken(), clientId);
     if (expectRefreshToken) {
       soft.assertThat(renewed.getTokens().getRefreshToken()).isNotNull();
+      soft.assertThat(renewed.getRefreshTokenExpirationTime()).isNotNull();
     } else {
       soft.assertThat(renewed.getTokens().getRefreshToken()).isNull();
     }
   }
 
-  private void introspectToken(AccessToken accessToken, String clientId) throws ParseException {
+  private JWT introspectToken(AccessToken accessToken, String clientId) throws ParseException {
     soft.assertThat(accessToken).isNotNull();
     JWT jwt = JWTParser.parse(accessToken.getValue());
     soft.assertThat(jwt).isNotNull();
     soft.assertThat(jwt.getJWTClaimsSet().getStringClaim("azp")).isEqualTo(clientId);
     soft.assertThat(jwt.getJWTClaimsSet().getStringClaim("scope")).contains(SCOPE1);
+    return jwt;
   }
 }

oauth2/core/src/main/java/com/dremio/iceberg/authmgr/oauth2/flow/TokensResult.java

@@ -90,7 +90,7 @@ public Instant getAccessTokenExpirationTime() {
     return exp != null ? exp : getAccessTokenJwtExpirationTime();
   }
 
-  @Value.Derived
+  @Value.Lazy
   @Nullable
   public Instant getRefreshTokenExpirationTime() {
     Instant exp = getRefreshTokenResponseExpirationTime();

oauth2/tests/src/main/java/com/dremio/iceberg/authmgr/oauth2/test/container/KeycloakContainer.java

@@ -234,7 +234,10 @@ protected void createClient(RealmResource master, ClientRepresentation client) {
       client.setAttributes(attributes);
     }
     client.setOptionalClientScopes(
-        scopes.stream().map(ClientScopeRepresentation::getName).collect(Collectors.toList()));
+        ImmutableList.<String>builder()
+            .addAll(scopes.stream().map(ClientScopeRepresentation::getName).iterator())
+            .add("offline_access")
+            .build());
     try (Response response = master.clients().create(client)) {
       if (response.getStatus() != 201) {
         throw new IllegalStateException(