### Question:
TracerSdk implements Tracer { @Override public Span.Builder spanBuilder(String spanName) { if (sharedState.isStopped()) { return DefaultTracer.getInstance().spanBuilder(spanName); } return new SpanBuilderSdk( spanName, instrumentationLibraryInfo, sharedState.getActiveSpanProcessor(), sharedState.getActiveTraceConfig(), sharedState.getResource(), sharedState.getIdsGenerator(), sharedState.getClock()); } TracerSdk(TracerSharedState sharedState, InstrumentationLibraryInfo instrumentationLibraryInfo); @Override Span getCurrentSpan(); @Override Scope withSpan(Span span); @Override Span.Builder spanBuilder(String spanName);  }### Answer:
@Test void defaultSpanBuilder() { assertThat(tracer.spanBuilder(SPAN_NAME)).isInstanceOf(SpanBuilderSdk.class); }