API: allow constructing pipeliner builders from pre-existing pipeline builders #25
Description
The is currently no way to derive a pipeline builder from an existing pipeline builder instance.
This type of feature is useful for situations such as having a Spring bean for a "base" pipeline builder instance, which other beans would fork from, tweak, and then build into their respective pipeline bean. We can already have something similar by creating "factory" functions instead, but in this case we need to explicitly wire all required arguments (which can introduce discrepancies).
The general idea is along the lines of:
var newBuilder = Pipeline.of(existingBuilder);