add get notifications features API

model/notifications/config.smithy

@@ -35,3 +35,26 @@ structure NotificationsConfigsOutputItem {
 list NotificationsConfigsList {
     member: NotificationsConfigsOutputItem
 }
+
+@xDataType("array")
+@xEnumOptions([
+    "slack",
+    "chime",
+    "microsoft_teams",
+    "webhook",
+    "email",
+    "sns",
+    "ses_account",
+    "smtp_account",
+    "email_group"
+])
+@documentation("Limit the information for notifications features list.")
+string NotificationsFeaturesListItem
+
+list NotificationsFeaturesList {
+    member: NotificationsFeaturesListItem
+}
+
+structure NotificationsPluginFeatures {
+    tooltip_support: Boolean
+}

model/notifications/features/operations.smithy

@@ -0,0 +1,23 @@
+//  SPDX-License-Identifier: Apache-2.0
+//
+//  The OpenSearch Contributors require contributions made to
+//  this file be licensed under the Apache-2.0 license or a
+//  compatible open source license.
+
+$version: "2"
+namespace OpenSearch
+
+@externalDocumentation(
+    "API Reference": "https://opensearch.org/docs/latest/observing-your-data/notifications/api/"
+)
+
+@xOperationGroup("notifications.features")
+@xVersionAdded("2.2")
+@readonly
+@suppress(["HttpUriConflict"])
+@http(method: "GET", uri: "/_plugins/_notifications/features")
+@documentation("Retrieve a list of all supported notification configuration types.")
+operation NotificationsFeatures_Get {
+    input: NotificationsFeatures_Get_Input,
+    output: NotificationsFeatures_Get_Output
+}

model/notifications/features/structures.smithy

@@ -0,0 +1,18 @@
+//  SPDX-License-Identifier: Apache-2.0
+//
+//  The OpenSearch Contributors require contributions made to
+//  this file be licensed under the Apache-2.0 license or a
+//  compatible open source license.
+
+$version: "2"
+namespace OpenSearch
+
+@input
+structure NotificationsFeatures_Get_Input {
+}
+
+@output
+structure NotificationsFeatures_Get_Output {
+    allowed_config_type_list: NotificationsFeaturesList,
+    plugin_features: NotificationsPluginFeatures
+}

model/opensearch.smithy

@@ -297,6 +297,7 @@ service OpenSearch {
         NodesUsage_WithNodeId,
         NotificationsConfigs_Get,
         NotificationsConfigs_Post,
+        NotificationsFeatures_Get,
         PatchActionGroup,
         PatchActionGroups,
         PatchAuditConfiguration,