Grouping Rule (grouping)

Groups data by specified columns and applies sub-rules to each group.

Field	Description	Required
columns	Array of column names to group by	✅ Yes
rules	Array of sub-rules to apply to each group	✅ Yes

Example:

{
    "type": "grouping",
    "columns": ["customer_id", "product_type"],
    "rules": [
        {"type": "trim_whitespace", "source_column": "description"}
    ]
}

Behavior: Groups data by customer and product type, then applies whitespace trimming to each group.