Change result type to accept multiple batches

[alchemist51]

Description

[Describe what this change achieves]

Related Issues

Resolves #[Issue number to be closed when this PR is merged]

Check List

• Functionality includes testing.
• API changes companion pull request created, if applicable.
• Public documentation issue/PR created, if applicable.

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[github-actions]

❌ Gradle check result for 098249a: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 15b6091: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions]

❌ Gradle check result for 830c897: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[expani]

Should we consider putting this inside it's own class, something like

interface DataFusionResult {
   void addResult(Object[] values);
   Object getValueAt(String key, int index);
}

class InMemoryDataFusionResult implements DataFusionResult { 
  Map<String, List<Object>> dfResults;
} 

If the initial implementation did this ( partially on me ), the change of Object[] -> List<Object[]> would be contained within this class and not require changes across all aggregators.

In future, if we use a different data structure it can be easily replaced as well.

[github-actions]

❌ Gradle check result for 20197ba: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[expani]

Thanks for the iteration @alchemist51