Offers a step-by-step fluent API to build a hash-join pipeline stage.
To obtain it, call
StreamStage#hashJoinBuilder() on the primary
stage, the one whose data will be enriched from all other stages.
Collect all the tags returned from
add() and use them to retrieve
the enriching items from
ItemsByTag you get in the result. Retrieve
the tag of the first stage (from which you obtained the builder) by calling
#tag0().
This object is mainly intended to build a hash-join of the primary stage
with three or more contributing stages. For one or two stages, prefer the
direct
stage.hashJoin(...) calls because they offer more static
type safety.