[SPARK-11319][SQL] Making StructField's nullable field documentation clearer #11785
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What changes were proposed in this pull request?
Be more descriptive in what the nullable field of StructField is intended for. At the moment, the description does not explain that it's only a hint to the optimizer, and many people are mistakenly thinking that this is a "NOT NULL" type constraint. Making it clear in the doc should help people understand its purpose.
How was this patch tested?
Not tested as it's only documentation