feat: add promote member support.

[mahanteshwar-git]

What this PR does

This PR adds support for promote member invocation for the new members which are added a learner nodes.

Why this is useful

The existing add members support adding member as a learner. However there is no support for promoting the
member as regular raft voting member. This feature attempts to address this.

Implementation Details

• Added a new method: promoteMember in the ClusterClient
• Updated ClusterMembersTest to include unit tests for invoking promoteMember

Related Issues / Discussions

This change was based on discussion in #1499

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Checklist

• Code compiles successfully
• Tests added / updated
• Documentation updated (if needed)
• Ready for review

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[mahanteshwar-git]

/approve

[k8s-ci-robot]

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In response to this:

/lgtm

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[mahanteshwar-git]

Hi @lburgazzoli , @fanminshi , @vorburger ,

Please review the pull request

[mahanteshwar-git]

fixed spotless errors.

[Copilot]

Pull Request Overview

This PR adds support for promoting etcd cluster members from learner (non-voting) status to full voting members through a new promoteMember API method.

• Implements the MemberPromote gRPC service endpoint with request/response message types
• Adds promoteMember method to the Cluster interface and ClusterImpl implementation
• Creates MemberPromoteResponse class to handle the promote operation response

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
jetcd-grpc/src/main/proto/rpc.proto	Adds MemberPromote gRPC service method and message definitions
jetcd-core/src/main/proto/rpc.proto	Duplicates the gRPC service method and message definitions
jetcd-core/src/main/java/io/etcd/jetcd/Cluster.java	Adds promoteMember method signature to Cluster interface
jetcd-core/src/main/java/io/etcd/jetcd/impl/ClusterImpl.java	Implements promoteMember method in ClusterImpl
jetcd-core/src/main/java/io/etcd/jetcd/cluster/MemberPromoteResponse.java	Creates response wrapper class for member promote operations
jetcd-core/src/test/java/io/etcd/jetcd/impl/ClusterMembersTest.java	Adds integration test for the new promoteMember functionality

Comments suppressed due to low confidence (1)

jetcd-core/src/test/java/io/etcd/jetcd/impl/ClusterMembersTest.java:131

• The test only verifies the failure case when promoting a learner that is not in sync with the leader. Consider adding a positive test case that successfully promotes a member when conditions are met, or at least verify the specific error message more precisely to ensure the correct API endpoint is being called.

        // Now attempt to promote a member. Although it fails, it confirms that API was executed.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lburgazzoli, mahanteshwar-git

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• OWNERS [lburgazzoli]

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[mahanteshwar-git]

Hi @vorburger,

Would it be possible to take another look at the Pr and approve if the changes look reasonable ?