[Issue 6024][pulsar_storm] PulsarSpout emit to multiple streams (#6039)
Fixes #6024
### Motivation
This is all described in detail in https://github.com/apache/pulsar/issues/6024, but in short, an insurmountable obstacle to using Pulsar in our storm topology is the fact that `PulsarSpout` only emits to the "default" stream. In our environment, we need to emit on different streams based on the content of each received message. This change extends `PulsarSpout` to recognize a `Values` extension that specifies an alternate output stream, and uses that stream when given.
### Modifications
A new `PulsarTuple` class is added. It extends `Values` and adds a method to return the output stream.
When emitting a tuple after calling `toValues(msg)`, `PulsarSpout` checks if the returned `Values` is a `PulsarTuple`. If so, it emits to the designated stream, otherwise it emits as before.
4 files changed
