Chenxi Li created ARROW-15126:
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Summary: [C++] Support Null type as group keys
Key: ARROW-15126
URL: https://issues.apache.org/jira/browse/ARROW-15126
Project: Apache Arrow
Issue Type: Improvement
Components: C++
Reporter: Chenxi Li-- This message was sent by Atlassian Jira (v8.20.1#820001)
