Function data_file_location 

fn data_file_location(configured_path: Option<&str>, location: &str) -> String

Returns the base location for the table’s data files, with no trailing separator.

configured_path is the catalog’s write.data.path, or write.folder-storage.path where only the older property is set. location is the table’s own location, used when the catalog configures neither.

The result never ends in /. Callers join it with a / and a file name, and the joined URI is what lands in the manifest, so a separator left on the end here produces a manifest entry naming an object that was never written.