Add support for retrieving connector offsets

[AfrinKhan02]

Context

Kafka Connect already exposes an endpoint to retrieve the current offsets of a connector.

This change adds support for that capability in Ns4Kafka to retrieve connector offsets directly from the connector API.

This PR focuses on offset retrieval only.

Related work:

• Full reset of connector offsets: Add a functionality to fully reset connector offsets #821
• Partial or altered connector offsets: Add functionality to support partial and altered connector offsets #826

Proposed solution

Add a new connector endpoint in Ns4Kafka to retrieve offsets for a given connector.

The goal is to keep the implementation aligned with the existing connector flow:

• call Kafka Connect through the existing client layer
• expose the capability through the service layer
• provide a dedicated controller endpoint for retrieval
• enforce the same ownership and access control rules as other connector subresources

Implementation

I introduced a dedicated response model for connector offsets and added a new Kafka Connect client call to query /connectors/{connector}/offsets.

I then wired this capability through the connector service so the controller can reuse the existing connector lookup and ownership checks.

On the API side, I added a new endpoint to retrieve offsets for a connector from the namespaced connector API.

The implementation keeps the returned partition and offset payload flexible, since Kafka Connect can return connector-defined structures depending on whether the connector is a source or a sink.

Tests

I added tests for:

• the Kafka Connect offsets retrieval flow through the connector service
• the controller endpoint behavior for successful retrieval and connector-not-found handling
• access control for the new connector offsets subresource in the security rule tests

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
91.3% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud