Task: throw error on implicit flow

src/Kiota.Builder/Plugins/PluginsGenerationService.cs

@@ -79,7 +79,7 @@
                     pluginDocument.Write(writer);
                     break;
                 case PluginType.APIManifest:
                     var apiManifest = new ApiManifestDocument("application"); //TODO add application name
                     // pass empty config hash so that its not included in this manifest.
                     apiManifest.ApiDependencies[Configuration.ClientClassName] = Configuration.ToApiDependency(string.Empty, TreeNode?.GetRequestInfo().ToDictionary(static x => x.Key, static x => x.Value) ?? [], WorkingDirectory);
                     var publisherName = string.IsNullOrEmpty(OAIDocument.Info?.Contact?.Name)
@@ -137,7 +137,7 @@
             }
             return newSchema;
         }
         static OpenApiSchema? MergeAllOfInSchema(OpenApiSchema? schema)
         {
             if (schema?.AllOf is not { Count: > 0 }) return schema;
             var newSchema = new OpenApiSchema();
@@ -414,7 +414,7 @@
             {
                 ReferenceId = $"{{{name}_REGISTRATION_ID}}"
             },
-            SecuritySchemeType.OAuth2 => new OAuthPluginVault
+            SecuritySchemeType.OAuth2 when securityScheme.Flows.AuthorizationCode != null => new OAuthPluginVault
             {
                 ReferenceId = $"{{{name}_CONFIGURATION_ID}}"
             },

tests/Kiota.Builder.Tests/Plugins/PluginsGenerationServiceTests.cs

@@ -398,6 +398,21 @@ public static TheoryData<string, string, string, PluginAuthConfiguration, Action
                     Assert.Equal("{oauth2_0_CONFIGURATION_ID}", ((OAuthPluginVault)auth0!).ReferenceId);
                 }
             },
+            // oauth2: implicit
+            {
+                "{securitySchemes: {oauth2_0: {type: oauth2, flows: {implicit: {}}}}}",
+                string.Empty, "security: [oauth2_0: []]", null, resultingManifest =>
+                {
+                    Assert.NotNull(resultingManifest.Document);
+                    Assert.Empty(resultingManifest.Problems);
+                    Assert.NotEmpty(resultingManifest.Document.Runtimes);
+                    var auth0 = resultingManifest.Document.Runtimes[0].Auth;
+                    Assert.IsType<OAuthPluginVault>(auth0);
+                    Assert.Equal(AuthType.OAuthPluginVault, auth0?.Type);
+                    Assert.Equal("{oauth2_0_CONFIGURATION_ID}", ((OAuthPluginVault)auth0!).ReferenceId);
+                }
+            },
+
             // should be anonymous
             {
                 "{}", string.Empty, "security: [invalid: []]", null, resultingManifest =>