[javier-aliaga]

Description

Fourth step of splitting DaprClientImpl into package-private classes, one per building block. This PR moves pub/sub.

• New package-private class DaprPubSubClient holds publishEvent, publishEvents (with the bulkPublishEventAlpha1 fallback), the subscribeToEvents and subscribeToTopic overloads, and buildSubscription. The bodies are unchanged.
• The two subscription paths built their stub with grpcInterceptors.intercept(asyncStub). They now call a new DaprGrpcCalls.intercept(), which makes the same call on the same stub and interceptors.
• DaprClientImpl no longer reads its asyncStub field, so the field is removed. DaprGrpcCalls still holds the stub.
• The subscription logger keeps the DaprClientImpl category, so existing log configuration still applies.
• The public methods on DaprClientImpl keep their signatures and Javadoc, and delegate in one line.
• No public API change. DaprClientImpl goes from 2,065 to 1,829 lines.

Issue reference

Part of #1875

Checklist

• Code compiles correctly
• Created/updated tests. DaprClientGrpcTest, DaprPreviewClientGrpcTest and SubscriptionTest cover pub/sub through the public methods. The 626 sdk unit tests pass unchanged.
• Extended the documentation. Not needed, internal change.

[Copilot]

🟢 Approval recommended

No active review issues are present, and the refactoring preserves the existing public pub/sub API while separating its implementation into a dedicated client.

No open issues 🎉

What changed in this PR

This PR refactors pub/sub operations out of DaprClientImpl into a package-private DaprPubSubClient, preserving the existing public API and behavior while reducing the main client's responsibilities.

Changes:

• Moved publishing and subscription implementations into DaprPubSubClient.
• Added shared async gRPC stub interception through DaprGrpcCalls.
• Updated DaprClientImpl to delegate pub/sub methods and removed its direct async stub dependency.

File	Description
sdk/​src/​main/​java/​io/​dapr/​client/​DaprPubSubClient.java	Adds the package-private implementation for pub/sub publishing, subscriptions, and subscription handling.
sdk/​src/​main/​java/​io/​dapr/​client/​DaprGrpcCalls.java	Adds shared interception of the async gRPC stub for calls without a Reactor context.
sdk/​src/​main/​java/​io/​dapr/​client/​DaprClientImpl.java	Initializes the pub/sub client and delegates the existing public pub/sub methods.

_{Review effort: Lite}

[artur-ciocanu]

Love it!

[codecov]

Codecov Report

❌ Patch coverage is 85.09317% with 24 lines in your changes missing coverage. Please review.
✅ Project coverage is 82.00%. Comparing base (c5969a0) to head (12e64d5).
⚠️ Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
...src/main/java/io/dapr/client/DaprPubSubClient.java	83.89%	12 Missing and 12 partials ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1905      +/-   ##
============================================
+ Coverage     81.93%   82.00%   +0.06%     
- Complexity     3651     3664      +13     
============================================
  Files           330      331       +1     
  Lines         11351    11367      +16     
  Branches       1290     1290              
============================================
+ Hits           9301     9322      +21     
+ Misses         1556     1550       -6     
- Partials        494      495       +1     

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