Function path_points_to_struct 

fn path_points_to_struct(
    parquet_schema_desc: &SchemaDescriptor,
    root_idx: usize,
    path: &[String],
) -> bool

Returns whether a nested path points to an explicitly materialized object.

JSON2 v2 can split an object’s children between its Struct field and the remainder, so reading the Struct leaves alone may produce an incomplete object.