fix PFR with readme and integ updates

Author: jamiepmullan

packages/@aws-cdk/aws-mediapackagev2-alpha/README.md

@@ -93,6 +93,25 @@ const channelGroup = ChannelGroup.fromChannelGroupAttributes(stack, 'ImportedCha
 });
 ```
 
+You can also import from an ARN, which automatically extracts the name and region:
+
+```ts
+declare const stack: Stack;
+const channelGroup = ChannelGroup.fromChannelGroupArn(stack, 'ImportedChannelGroup',
+    'arn:aws:mediapackagev2:us-west-2:123456789012:channelGroup/MyChannelGroup',
+);
+```
+
+For cross-region imports, pass the `region` parameter to ensure the correct ARN is constructed:
+
+```ts
+declare const stack: Stack;
+const channelGroup = ChannelGroup.fromChannelGroupAttributes(stack, 'ImportedChannelGroup', {
+    channelGroupName: 'MyChannelGroup',
+    region: 'us-west-2',
+});
+```
+
 ## Channel
 
 A channel is part of a channel group and represents the entry point for a content stream into MediaPackage.
@@ -140,6 +159,17 @@ const channel = Channel.fromChannelAttributes(stack, 'ImportedChannel', {
 });
 ```
 
+You can also import from an ARN:
+
+```ts
+declare const stack: Stack;
+const channel = Channel.fromChannelArn(stack, 'ImportedChannel',
+    'arn:aws:mediapackagev2:us-west-2:123456789012:channelGroup/MyGroup/channel/MyChannel',
+);
+```
+
+Imported channels expose a `region` property, which is parsed from the ARN or falls back to the importing stack's region.
+
 ### Channel Resource Policy
 
 The following code creates a resource policy directly on the channel. This 
@@ -184,6 +214,15 @@ const originEndpoint = OriginEndpoint.fromOriginEndpointAttributes(stack, 'Impor
 });
 ```
 
+You can also import from an ARN:
+
+```ts
+declare const stack: Stack;
+const originEndpoint = OriginEndpoint.fromOriginEndpointArn(stack, 'ImportedOriginEndpoint',
+    'arn:aws:mediapackagev2:us-west-2:123456789012:channelGroup/MyGroup/channel/MyChannel/originEndpoint/MyEndpoint',
+);
+```
+
 The following code creates a resource policy on the origin endpoint. This 
 will automatically create a policy on the first call:
 

packages/@aws-cdk/aws-mediapackagev2-alpha/test/integ.mediapackagev2-import-channel.js.snapshot/aws-cdk-mediapackagev2-import-channel.assets.json

@@ -0,0 +1,92 @@
+{
+ "Resources": {
+  "GroupC77FDACD": {
+   "Type": "AWS::MediaPackageV2::ChannelGroup",
+   "Properties": {
+    "ChannelGroupName": "import-test-group"
+   },
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
+  },
+  "Channel4048F119": {
+   "Type": "AWS::MediaPackageV2::Channel",
+   "Properties": {
+    "ChannelGroupName": "import-test-group",
+    "ChannelName": "import-test-channel",
+    "InputType": "CMAF"
+   },
+   "DependsOn": [
+    "GroupC77FDACD"
+   ],
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
+  },
+  "EndpointEEF1FD8F": {
+   "Type": "AWS::MediaPackageV2::OriginEndpoint",
+   "Properties": {
+    "ChannelGroupName": "import-test-group",
+    "ChannelName": "import-test-channel",
+    "ContainerType": "CMAF",
+    "DashManifests": [
+     {
+      "ManifestName": "dash-index"
+     }
+    ],
+    "HlsManifests": [
+     {
+      "ManifestName": "hls-index"
+     }
+    ],
+    "OriginEndpointName": "import-test-endpoint",
+    "Segment": {}
+   },
+   "DependsOn": [
+    "Channel4048F119",
+    "GroupC77FDACD"
+   ],
+   "UpdateReplacePolicy": "Delete",
+   "DeletionPolicy": "Delete"
+  }
+ },
+ "Outputs": {
+  "ImportedChannelRegion": {
+   "Value": {
+    "Ref": "AWS::Region"
+   }
+  }
+ },
+ "Parameters": {
+  "BootstrapVersion": {
+   "Type": "AWS::SSM::Parameter::Value<String>",
+   "Default": "/cdk-bootstrap/hnb659fds/version",
+   "Description": "Version of the CDK Bootstrap resources in this environment, automatically retrieved from SSM Parameter Store. [cdk:skip]"
+  }
+ },
+ "Rules": {
+  "CheckBootstrapVersion": {
+   "Assertions": [
+    {
+     "Assert": {
+      "Fn::Not": [
+       {
+        "Fn::Contains": [
+         [
+          "1",
+          "2",
+          "3",
+          "4",
+          "5"
+         ],
+         {
+          "Ref": "BootstrapVersion"
+         }
+        ]
+       }
+      ]
+     },
+     "AssertDescription": "CDK bootstrap stack version 6 required. Please run 'cdk bootstrap' with a recent version of the CDK CLI."
+    }
+   ]
+  }
+ }
+}