Find the first DocumentIdColumn output field that has a 'dependent' property and extract its dependent field name.
Returns the dependent field name (e.g., 'table_name', 'source_table') or never if none found.
Only considers DocumentIdColumn outputs, not other columns that might have a dependent property.
Find the first DocumentIdColumn output field that has a 'dependent' property and extract its dependent field name. Returns the dependent field name (e.g., 'table_name', 'source_table') or never if none found. Only considers DocumentIdColumn outputs, not other columns that might have a dependent property.