### Question:
Adapter { @VisibleForTesting static Model.SpanRef toSpanRef(Link link) { Model.SpanRef.Builder builder = Model.SpanRef.newBuilder(); builder.setTraceId(TraceProtoUtils.toProtoTraceId(link.getContext().getTraceIdAsHexString())); builder.setSpanId(TraceProtoUtils.toProtoSpanId(link.getContext().getSpanIdAsHexString())); builder.setRefType(Model.SpanRefType.FOLLOWS_FROM); return builder.build(); } private  Adapter();   }### Answer:
@Test void testSpanRef() { Link link = Link.create(createSpanContext(TRACE_ID, SPAN_ID)); Model.SpanRef spanRef = Adapter.toSpanRef(link); assertEquals(TraceProtoUtils.toProtoSpanId(SPAN_ID), spanRef.getSpanId()); assertEquals(TraceProtoUtils.toProtoTraceId(TRACE_ID), spanRef.getTraceId()); assertEquals(Model.SpanRefType.FOLLOWS_FROM, spanRef.getRefType()); }