Produces the self-contained fat jar that the Python wheel mounts via --jars, for Spark 4.2.x / Scala 2.13 (WP-20). WHY THIS BUNDLE RECOMPILES THE VERSION-AGNOSTIC LAYERS ------------------------------------------------------ The 3.5 bundles ship api/dispatch/runtime classes compiled against Spark 3.5.3. Those classes are SOURCE-identical here, but a Spark 4.2 driver cannot link against classes whose erased Catalyst descriptors were built for 3.5 when the 4.2 Catalyst ...