Regarding to documentation
Functional in nature. An operation on a stream produces a result, but does not modify its source. For example, filtering a Stream obtained from a collection produces a new Stream without the filtered elements, rather than removing elements from the source collection.
It returns a
DoubleStream, which supports
sequential and parallel aggregate operations
This is why it not works.
Edit: The first section was incorrect. Replaced it by a more correct version
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