Expand description
Linear operator chain DSL (map, filter, flat_map, sink, name).
Build-time errors on the chain panic (duplicate source, steps after terminal sink).
Runtime errors use [crate::api::error::StreamResult] in crate::stream::chain_execute::execute.
Terminate with DataStream::sink, [crate::connectors::print::PrintDataStreamExt::print], or
[crate::connectors::iceberg::data_stream_ext::IcebergDataStreamExt::add_iceberg_sink],
then crate::env::stream_env::StreamEnv::execute.