NIFI-15717: Add QueryCassandra processor and CassandraSessionProvider Controller Service.

[vishal-firgan-ksolves]

…r Service.

Summary

NIFI-15717

This PR introduces the QueryCassandra processor for Apache NiFi 2.x, enabling integration with Cassandra using the latest DataStax Java driver.

Components Added

• QueryCassandra processor for executing CQL queries
• CassandraSessionProvider Controller Service for managing connections

Tracking

Please complete the following tracking steps prior to pull request creation.

Issue Tracking

• Apache NiFi Jira issue created

Pull Request Tracking

• Pull Request title starts with Apache NiFi Jira issue number, such as NIFI-00000
• Pull Request commit message starts with Apache NiFi Jira issue number, as such NIFI-00000
• Pull request contains commits signed with a registered key indicating Verified status

Pull Request Formatting

• Pull Request based on current revision of the main branch
• Pull Request refers to a feature branch with one commit containing changes

Verification

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Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy
• New dependencies are documented in applicable LICENSE and NOTICE files

Documentation

• Documentation formatting appears as expected in rendered files

[exceptionfactory]

Thanks for putting together this down-scoped pull request. I'm planning to take a closer look soon, but it provides a good basis for initial review.

One initial element to consider is the data type handling in the AbstractCassandraProcessor. It seems like it would be best to pull that out to a separate interface and implementation, perhaps several depending on the details. The general goal there is to decouple type conversion from the Processor itself, so that it can be used in composition, rather than by extension in other Cassandra Processors.

[vishal-firgan-ksolves]

@exceptionfactory I’ve implemented the changes to decouple type conversion from AbstractCassandraProcessor into a new CassandraTypeConverter interface with StandardCassandraTypeConverter as its implementation.
Please review the changes.