feat: add ServiceLoader support for plugin.discovery=service_load

[Yashwanth-NS-07]

Problem

Explained in issue #1567

Root Cause Analysis

The issue appears to be that kafka-connect-jdbc is missing the required ServiceLoader configuration files.

For ServiceLoader to discover connector implementations, the JAR needs to contain:

• META-INF/services/org.apache.kafka.connect.source.SourceConnector
• META-INF/services/org.apache.kafka.connect.sink.SinkConnector

These files should list the fully qualified class names of the connector implementations.

Proposed Solution

Add ServiceLoader configuration files to the kafka-connect-jdbc JAR:

1. Create Source Connector Service File

File: META-INF/services/org.apache.kafka.connect.source.SourceConnector

io.confluent.connect.jdbc.JdbcSourceConnector

2. Create Sink Connector Service File

File: META-INF/services/org.apache.kafka.connect.sink.SinkConnector

io.confluent.connect.jdbc.JdbcSinkConnector

Does this solution apply anywhere else?

: yes

If yes, where?

here: https://github.com/apache/kafka/tree/trunk/connect/file/src/main/resources/META-INF/services

Test Strategy

Manual Testing Performed

I manually tested this change by spinning up Kafka brokers and Connect servers locally.

Test Environment

• Kafka brokers running locally
• Kafka Connect server in distributed mode
• Configuration: plugin.discovery=service_load

Test Steps

1. Started local Kafka brokers
2. Configured Kafka Connect with plugin.discovery=service_load
3. Added kafka-connect-jdbc JAR with ServiceLoader configuration
4. Started Kafka Connect server
5. Verified connector discovery via REST API:

   curl http://localhost:8083/connector-plugins

Release Plan

Proposed Approach

• Merge to master branch for next release
• Consider backporting to active maintenance branches (if applicable)

Compatibility

• ✅ Backward compatible - no breaking changes
• ✅ Safe to merge - only adds new functionality
• ✅ No rollback concerns - existing discovery modes unaffected

Suggested Target

• Next minor/patch release

[confluent-cla-assistant]

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✅ Yashwanth-NS-07
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