experimental catalog CSVDataSource emits warnings

[vpipkt]

During docs build I see a lot of this, even after cleaning up ~/.rf_cache dir.

WARN CSVDataSource: CSV header does not conform to the schema.
 Header: productId, entityId, acquisitionDate, cloudCover, processingLevel, path, row, min_lat, min_lon, max_lat, max_lon, download_url
 Schema: product_id, entity_id, acquisition_date, cloud_cover_pct, processing_level, path, row, min_lat, min_lon, max_lat, max_lon, download_url
Expected: product_id but found: productId
CSV file: file:///Users/jbrown/.rf_cache/scene_list-35bc8c4913b62c16282cb33dde3e533f.gz

[metasim]

Thank you Spark 2.4.x