Tracer { public SpanInScope withSpanInScope(@Nullable Span span) { return new SpanInScope(currentTraceContext.newScope(span != null ? span.context() : null)); } Tracer(
    Clock clock,
    Propagation.Factory propagationFactory,
    SpanHandler spanHandler,
    PendingSpans pendingSpans,
    Sampler sampler,
    CurrentTraceContext currentTraceContext,
    boolean traceId128Bit,
    boolean supportsJoin,
    boolean alwaysSampleLocal,
    AtomicBoolean noop
  ); @Deprecated Tracer withSampler(Sampler sampler); Span newTrace(); final Span joinSpan(TraceContext context); Span newChild(TraceContext parent); Span nextSpan(TraceContextOrSamplingFlags extracted); Span toSpan(TraceContext context); SpanInScope withSpanInScope(@Nullable Span span); SpanCustomizer currentSpanCustomizer(); @Nullable Span currentSpan(); Span nextSpan(); ScopedSpan startScopedSpan(String name); ScopedSpan startScopedSpan(String name, SamplerFunction<T> samplerFunction, T arg); Span nextSpan(SamplerFunction<T> samplerFunction, T arg); Span nextSpanWithParent(SamplerFunction<T> samplerFunction, T arg,
    @Nullable TraceContext parent); ScopedSpan startScopedSpanWithParent(String name, @Nullable TraceContext parent); @Override String toString();  }
@Test public void withSpanInScope() { Span current = tracer.newTrace(); try (SpanInScope ws = tracer.withSpanInScope(current)) { assertThat(tracer.currentSpan()) .isEqualTo(current); assertThat(tracer.currentSpanCustomizer()) .isNotEqualTo(current) .isNotEqualTo(NoopSpanCustomizer.INSTANCE); } assertThat(tracer.currentSpan()).isNull(); }