* Make BaseTracer fields private
By making `tracer` private we're forcing all tracer implementation to use the `spanBuilder()` utility method and pass the parent context manually.
* testing-common refactoring: replace direct AgentTestRunner usage with spock spec
* Updated instrumentation docs
* Fix reactor-core library tests
ReactorCoreTest was getting a tracer from GlobalOpenTelemetry before LibraryTestTrait had a change to initialize the SDK
* Hide the context keys in the BaseTracer.
Provide the appropriate methods to get access.
* key needs to be static
* put all the span suppression logic in the BaseTracer
* the formatter is our friend
* rename method and add tests
* tests that work!
* Hide the context keys in the BaseTracer.
Provide the appropriate methods to get access.
* key needs to be static
* fix formatting
* more formatting, sigh
* remove an errant semicolon
Mateusz Rzeszutek
Trask Stalnaker
Anuraag Agrawal
John Watson
Pavol Loffay