Bump github.com/uber/jaeger-client-go

Bumps [github.com/uber/jaeger-client-go](https://github.com/uber/jaeger-client-go) from 2.19.0+incompatible to 2.20.0+incompatible.
- [Release notes](https://github.com/uber/jaeger-client-go/releases)
- [Changelog](https://github.com/jaegertracing/jaeger-client-go/blob/master/CHANGELOG.md)
- [Commits](https://github.com/uber/jaeger-client-go/compare/v2.19.0...v2.20.0)

Signed-off-by: dependabot-preview[bot] <support@dependabot.com>
Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/github.com/uber/jaeger-client-go/sampler_v2.go

@@ -0,0 +1,93 @@
+// Copyright (c) 2019 Uber Technologies, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package jaeger
+
+// SamplingDecision is returned by the V2 samplers.
+type SamplingDecision struct {
+	Sample    bool
+	Retryable bool
+	Tags      []Tag
+}
+
+// SamplerV2 is an extension of the V1 samplers that allows sampling decisions
+// be made at different points of the span lifecycle.
+type SamplerV2 interface {
+	OnCreateSpan(span *Span) SamplingDecision
+	OnSetOperationName(span *Span, operationName string) SamplingDecision
+	OnSetTag(span *Span, key string, value interface{}) SamplingDecision
+	OnFinishSpan(span *Span) SamplingDecision
+
+	// Close does a clean shutdown of the sampler, stopping any background
+	// go-routines it may have started.
+	Close()
+}
+
+// samplerV1toV2 wraps legacy V1 sampler into an adapter that make it look like V2.
+func samplerV1toV2(s Sampler) SamplerV2 {
+	if s2, ok := s.(SamplerV2); ok {
+		return s2
+	}
+	type legacySamplerV1toV2Adapter struct {
+		legacySamplerV1Base
+	}
+	return &legacySamplerV1toV2Adapter{
+		legacySamplerV1Base: legacySamplerV1Base{
+			delegate: s.IsSampled,
+		},
+	}
+}
+
+// SamplerV2Base can be used by V2 samplers to implement dummy V1 methods.
+// Supporting V1 API is required because Tracer configuration only accepts V1 Sampler
+// for backwards compatibility reasons.
+// TODO (breaking change) remove this in the next major release
+type SamplerV2Base struct{}
+
+// IsSampled implements IsSampled of Sampler.
+func (SamplerV2Base) IsSampled(id TraceID, operation string) (sampled bool, tags []Tag) {
+	return false, nil
+}
+
+// Close implements Close of Sampler.
+func (SamplerV2Base) Close() {}
+
+// Equal implements Equal of Sampler.
+func (SamplerV2Base) Equal(other Sampler) bool { return false }
+
+// legacySamplerV1Base is used as a base for simple samplers that only implement
+// the legacy isSampled() function that is not sensitive to its arguments.
+type legacySamplerV1Base struct {
+	delegate func(id TraceID, operation string) (sampled bool, tags []Tag)
+}
+
+func (s *legacySamplerV1Base) OnCreateSpan(span *Span) SamplingDecision {
+	isSampled, tags := s.delegate(span.context.traceID, span.operationName)
+	return SamplingDecision{Sample: isSampled, Retryable: false, Tags: tags}
+}
+
+func (s *legacySamplerV1Base) OnSetOperationName(span *Span, operationName string) SamplingDecision {
+	isSampled, tags := s.delegate(span.context.traceID, span.operationName)
+	return SamplingDecision{Sample: isSampled, Retryable: false, Tags: tags}
+}
+
+func (s *legacySamplerV1Base) OnSetTag(span *Span, key string, value interface{}) SamplingDecision {
+	return SamplingDecision{Sample: false, Retryable: true}
+}
+
+func (s *legacySamplerV1Base) OnFinishSpan(span *Span) SamplingDecision {
+	return SamplingDecision{Sample: false, Retryable: true}
+}
+
+func (s *legacySamplerV1Base) Close() {}