fix(cognito): do not return optional blocks in CreateUserPoolClient when they are not set

[b6k-dev]

Summary

Closes #1505

Changes summary:

• Omit optional blocks when serialzing CreateUserPoolClient
• Add unit tests
• Add compatibility tests for: Java SDK, terraform and opentofu

Type of change

• Bug fix (fix:)
• New feature (feat:)
• Breaking change (feat!: or fix!:)
• Docs / chore

AWS Compatibility

Incorrect behavior: CreateUserPoolClient returned "AnalyticsConfiguration": {} , "TokenValidityUnits": {} , and "RefreshTokenRotation": {} in the response body when those fields were not configured.

Fixed behavior: Optional block fields are now omitted from the CreateUserPoolClient response when not set.

Checklist

• ./mvnw test passes locally
• New or updated integration test added
• Commit messages follow Conventional Commits

[greptile-apps]

Greptile Summary

This PR fixes a serialization bug in Floci's Cognito emulator where CreateUserPoolClient (and by extension DescribeUserPoolClient / UpdateUserPoolClient) was returning empty JSON objects ({}) for AnalyticsConfiguration, TokenValidityUnits, and RefreshTokenRotation when those optional blocks were not configured, breaking Terraform/OpenTofu provider parsing.

• Core fix in CognitoJsonHandler.clientToNode: replaces the value != null ? value : new HashMap<>() pattern with Optional.ofNullable(...).ifPresent(...), so absent fields are simply omitted from the JSON response.
• Unit tests added at both the service level (CognitoServiceTest) and JSON-serialization level (CognitoJsonHandlerTest), plus a Java SDK compatibility test and Terraform/OpenTofu end-to-end tests to prevent regression.

Confidence Score: 5/5

Safe to merge — the change is a narrow, well-tested serialization fix with no impact on request parsing or business logic.

The fix is confined to three lines in the shared clientToNode serialization method. It has no effect on how requests are parsed or how the service stores state — only on which fields are emitted in the response. Coverage is thorough: service-layer null assertions, JSON-serialization assertions, a Java SDK end-to-end test, and Terraform/OpenTofu apply tests. No regressions are introduced for callers that do set these optional fields, since Optional.ifPresent still emits them when non-null.

No files require special attention.

Important Files Changed

Filename	Overview
src/main/java/io/github/hectorvent/floci/services/cognito/CognitoJsonHandler.java	Core fix: replaces empty-map fallback with Optional.ifPresent for AnalyticsConfiguration, TokenValidityUnits, and RefreshTokenRotation in clientToNode; applies correctly to all three client operations (Create/Describe/Update) since they share this method.
src/test/java/io/github/hectorvent/floci/services/cognito/CognitoJsonHandlerTest.java	New test createUserPoolClientDoesNotReturnOptionalBlockKeysWhenNotSet verifies that absent fields are omitted from the serialized JSON response; covers the serialization layer accurately.
src/test/java/io/github/hectorvent/floci/services/cognito/CognitoServiceTest.java	New test createUserPoolClientWithNoOptionalBlocksLeavesThemNull confirms the service model layer returns null for the three optional fields when not provided; logically sound.
compatibility-tests/sdk-test-java/src/test/java/com/floci/test/CognitoFeaturesTest.java	SDK compatibility test verifies AWS Java SDK correctly deserializes a response with absent optional blocks as null; cleanup correctly deletes the new client before the pool.
compatibility-tests/compat-terraform/main.tf	Adds aws_cognito_user_pool_client resource referencing the pre-existing pool, enabling the end-to-end Terraform apply test.
compatibility-tests/compat-terraform/test/terraform.bats	Bats test verifies the pool client was successfully created (non-empty, non-None ClientId), including the non-empty guard requested in prior review feedback.
compatibility-tests/compat-opentofu/main.tf	Adds both the Cognito user pool and its client resource to the OpenTofu configuration; names match what the bats test queries for.
compatibility-tests/compat-opentofu/test/opentofu.bats	Mirrors the Terraform bats test; verifies client existence after apply with non-empty and non-None guards.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
    participant Client as AWS SDK / Terraform
    participant Handler as CognitoJsonHandler
    participant Service as CognitoService
    participant Model as UserPoolClient (model)

    Client->>Handler: CreateUserPoolClient (no optional blocks)
    Handler->>Service: createUserPoolClient(poolId, name, ...)
    Service->>Model: "new UserPoolClient (analyticsConfiguration=null, tokenValidityUnits=null, refreshTokenRotation=null)"
    Service-->>Handler: UserPoolClient
    Handler->>Handler: clientToNode(client)
    Note over Handler: Optional.ofNullable(null).ifPresent(...) fields are OMITTED (not emitted as {})
    Handler-->>Client: "{UserPoolClient: {ClientId: ...}} (no AnalyticsConfiguration, TokenValidityUnits, RefreshTokenRotation keys)"

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sequenceDiagram
    participant Client as AWS SDK / Terraform
    participant Handler as CognitoJsonHandler
    participant Service as CognitoService
    participant Model as UserPoolClient (model)

    Client->>Handler: CreateUserPoolClient (no optional blocks)
    Handler->>Service: createUserPoolClient(poolId, name, ...)
    Service->>Model: "new UserPoolClient (analyticsConfiguration=null, tokenValidityUnits=null, refreshTokenRotation=null)"
    Service-->>Handler: UserPoolClient
    Handler->>Handler: clientToNode(client)
    Note over Handler: Optional.ofNullable(null).ifPresent(...) fields are OMITTED (not emitted as {})
    Handler-->>Client: "{UserPoolClient: {ClientId: ...}} (no AnalyticsConfiguration, TokenValidityUnits, RefreshTokenRotation keys)"

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_{Reviews (2): Last reviewed commit: "fix(cognito): improve bats assertions" | Re-trigger Greptile}

[b6k-dev]

https://github.com/floci-io/floci/actions/runs/28461093249/job/84350196672?pr=1615 - seems like a Docker build cache issue not related to my changes

[hectorvent]

Thanks @b6k-dev,
Solid fix