FOLLOWS_FROM reference adds redundant CHILD_OF reference in v1.5.0

[jpwilliams]

Requirement - what kind of business use case are you trying to solve?

Displaying relationships between services communicating using a message bus.

Problem - what in Jaeger blocks you from solving the requirement?

When creating a span with a single FOLLOWS_FROM reference, the UI's JSON export reveals that two references are actually created: a FOLLOWS_FROM reference as expected, but also a CHILD_OF reference, both with identical traceID and spanID fields.

Proposal - what do you suggest to solve the problem or improve the existing situation?

Discussion with @black-adder has revealed that the issue occurs in v1.5.0, but not in v1.4.1. @black-adder sees that the issue has likely been created in #831.

Any open questions to address

No questions.

Additional info

Here is a gist containing some example code to run to reproduce the problem, as well as the JSON exported in the problem version (v1.5.0). In v1.4.1, the references array correctly contains only the FOLLOWS_FROM reference.

https://gist.github.com/jpwilliams/1901cefdaff283ca3afcf5eb45375dbf

[yurishkuro]

ack