[SPARK-44528] Spark Connect DataFrame does not allow to add custom instance attributes and check for it

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.4.1
• Fix Version/s: 3.5.0, 4.0.0
• Component/s: Connect
• Assignee: Martin Grund
• Reporter: Martin Grund
• Created: 24/Jul/23 20:32
• Updated: 26/Jul/23 23:54
• Resolved: 26/Jul/23 23:54

Description

```
df = spark.range(10)
df._test = 10

assert(hasattr(df, "_test"))
assert(!hasattr(df, "_test_no"))
```

Treats `df._test` like a column