Github user revans2 commented on the issue:
https://github.com/apache/storm/pull/2882
@kishorvpatil
I didn't intend the data to be true JSON. There are some things Thrift
supports that JSON does not, like non-string map keys. Storm uses those in our
thrift data structures.
The goal is to be able to get something out that a human can look at and
understand.
To me `not set` is less ambiguous than `"not set"`, `""`, or `{}` because
it would never parse as JSON and it is actually not set. A `null` would
probably be fine seeing how setting something to null in thrift is the same as
not setting it.
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