implement polymorphism support for DynamoDB entries

[irina-herciu]

• implement DynamoDBPolymorphicPropertyAttribute for polymorphism support that should solve Saving nested items with class hierarchies Saving nested items with class hierarchies #2985

• implement DynamoDBPolymorphicTypeAttribute for polymorphism support for table entries

Description

New DynamoDB PropertyAttribute added as DynamoDBPolymorphicPropertyAttribute in order to add support for polymorphic property types serialization and deserialization
[DynamoDBPolymorphicProperty("B", typeof(B))]

New DynamoDB Attribute added as DynamoDBPolymorphicTypeAttribute in order to add support for polymorphic types serialization and deserialization
[DynamoDBPolymorphicType("A2", typeof(ModelA2))]

Type Attribute name can be configurable from DerivedTypeAttributeName on DynamoDBContextConfig and by default uses "$type".

Motivation and Context

#2985

Testing

Integration tests added

Screenshots (if appropriate)

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project
• My change requires a change to the documentation
• I have updated the documentation accordingly
• I have read the README document
• I have added tests to cover my changes
• All new and existing tests passed

License

• I confirm that this pull request can be released under the Apache 2 license

[dscpinheiro]

Can the other PR (that was targeting V3) - #3633 - be closed?

[irina-herciu]

@dscpinheiro the issue that the PR has in scope to fix was affecting AWSSDK.DynamoDBv2 3.7.104, but as @normj instructed in #3633 the fix is raised for V4 also.

[dscpinheiro]

Ok, my read from Norm's comment in the other PR was that we should only make this change for V4.

But I can double-check with him offline.

[normj]

@irina-herciu Can you add a change file like you did in your previous PR. https://github.com/aws/aws-sdk-net/pull/3614/files

[normj]

@irina-herciu A concern I have is a user saves the item with .NET but another parts reads the item with a different language have a mechanism that only stores the .NET type won't be portable. The AWS Kotlin SDK has similar support for polymorphism in their high level. It supports a mechanism customers can use to control the identifier for the type and they could potentially use a language neutral identifier. Can you rework this to have some sort of system that allows users to register a type conversation mapping. By default it can rely on .NET type but if a user can opt-in their own mechanism that would unblock polyglot customers.

Validation should be a customer can save a item using polymorphism in our Kotlin SDK and have a way to read it back out using your changes. My understanding in the Kotlin SDK you use the HeterogenerousItemConverter https://sdk.amazonaws.com/kotlin/api/latest/dynamodb-mapper/aws.sdk.kotlin.hll.dynamodbmapper.items/-heterogeneous-item-converter/index.html

[irina-herciu]

@normj The functionality implemented of this feature is different from the 'HeterogenerousItemConverter', as the Kotlin SDK feature is designed to convert top-level items in a DynamoDB table, meaning it applies polymorphism only when retrieving or saving items at the root level and requires a custom 'AttributeConverter' to handle polymorphic nested items.

[irina-herciu]

@irina-herciu Can you add a change file like you did in your previous PR. https://github.com/aws/aws-sdk-net/pull/3614/files

Change file added