[maven-release-plugin] copy for tag 0.21.0 

Move GlobalTracer from contrib to opentracing-java. (opentracing#109) * Move GlobalTracer from contrib to opentracing-java. * Use ReadWriteLock instead of AtomicReference. This avoids hotspinning (potentially with the UpdateFunction) on contention. Copied from opentracing-contrib/java-globaltracer#8 * Replace ReadWriteLock with Reentrant (write) Lock and volatile variable. Copied from opentracing-contrib/java-globaltracer#8 * Rename opentracing-globaltracer to opentracing-util module. Introduced the `io.opentracing.util` package. * Make sure to provide the 'current' tracer to the update function. Lazy load if that hasn't happened yet. * Fix typo (thanks @pavolloffay). * Simplify first GlobalTracer version to 'register' + 'get' only. * Initialize GlobalTracer to NoopTracer instance. * Fix unit tests. * Run mvn license:format * Minor textual cleanup. * Fix dependencyManagement in parent pom. * Process review comments. * Move mockito dependency to parent (thanks @pavolloffay) * Remove hamcrest library from util. It wasn't necessary. * Remove volatile and add synchronized to register(). This actually fixes multiple register() calls making it through (added unit-test that failed and now passes). * Explain limitations + nit: enclose throw in {} * don't need else (thanks @yurishkuro) * Simplify 'if' by reversing double-negative 'and' to positive 'or'. * Fix auto-formatted license by IntelliJ. * Remove hamcrest version declaration. It is no longer used. * Be consistent in groupId declaration in opentracing-util pom. * Readability: ..Tracer to delegate to -> Tracer delegate * Readability: ..Explicitly configures -> Register * Move equals() check to appropriate if-branch. * Print wrapped tracer in GlobalTracer.toString() * Rename `globalTracer` static var to `tracer`. @yurishkuro rename of internal variable is fine by me.

[maven-release-plugin] copy for tag 0.20.10 

Add the 'message_bus.destination' tag (opentracing#106) Add a new tag for messaging.

[maven-release-plugin] copy for tag 0.20.9 

[maven-release-plugin] copy for tag 0.20.8 

MockSpan throw ex when setting data after finish (opentracing#98) 

Allow consumers to define tags (opentracing#96) I think we all agree to merge this.

[maven-release-plugin] copy for tag 0.20.7 

[maven-release-plugin] copy for tag 0.20.6