[FLINK-28723] Fix json format failed to serialize the MapData when its key is not STRING

• Type: Sub-task
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: Formats (JSON, Avro, Parquet, ORC, SequenceFile)
• Assignee: Unassigned
• Reporter: Shengkai Fang
• Created: 28/Jul/22 01:46
• Updated: 09/Aug/22 15:58

Description

Currently, the JSON format only supports serializing the Map when its key is STRING. We may convert the key to a JSON string. For example, we can convert the `MAP<ARRAY<INT>, ARRAY<INT>>` to the following string.

{
  "[1, 2, 3]": [
    1,
    2,
    3
  ]
}