This does two things: ensures samples don't use Zipkin v1 in any way,
and misaligns the version numbers of zipkin v1 and zipkin v2 apis.
This is an attempt to walk around the gradle plugin issue, which only
exists when someone is using both versions of zipkin.
See https://github.com/spring-projects/spring-boot/issues/10778
without this change when an executor implementation was a final class or had a final method - the application wouldn't start or would produce NPE at startup.
with this change we have a custom bean post processor that wraps an aspect manualy either via a JDK Proxy when a class is final or a method is final or creates a CGLIB proxy if that's possible.
fixes#550
Brave's span collector, which turned out to not be a great tool for
direct use. Brave internally creates spans before sending to its
collector, so validation is implicit. The flip side of this is using the
collector directly does not validate spans. This means it is easy to
send invalid ones, for example missing span names. The problem is more
difficult as the data is in binary (thrift).
This introduces HttpZipkinSpanReporter, which validates via zipkin-java
classes before sending on the wire. Moreover, this sends in json to make
debugging problems easier.
This does not fully remove the Brave dependency, as further work is
needed. Particularly, Brave is indirectly referenced in other code.
See https://github.com/openzipkin/zipkin-java/issues/68
See #98 (Reporter is an OpenTracing term)
Recent versions of zipkin and brave operate with http instead of scribe.
This changes the implementation accordingly, as well adds a sampler to
the POST endpoint.
A notable impact is that we no longer require a collector process, as
the zipkin server's POST endpoint is a collector.
