### Question:
SpanAdapter { static Span.SpanKind toProtoSpanKind(Kind kind) { switch (kind) { case INTERNAL: return SPAN_KIND_INTERNAL; case SERVER: return SPAN_KIND_SERVER; case CLIENT: return SPAN_KIND_CLIENT; case PRODUCER: return SPAN_KIND_PRODUCER; case CONSUMER: return SPAN_KIND_CONSUMER; } return SpanKind.UNRECOGNIZED; } private  SpanAdapter();   }### Answer:
@Test void toProtoSpanKind() { assertThat(SpanAdapter.toProtoSpanKind(Kind.INTERNAL)).isEqualTo(SPAN_KIND_INTERNAL); assertThat(SpanAdapter.toProtoSpanKind(Kind.CLIENT)).isEqualTo(SPAN_KIND_CLIENT); assertThat(SpanAdapter.toProtoSpanKind(Kind.SERVER)).isEqualTo(SPAN_KIND_SERVER); assertThat(SpanAdapter.toProtoSpanKind(Kind.PRODUCER)).isEqualTo(SPAN_KIND_PRODUCER); assertThat(SpanAdapter.toProtoSpanKind(Kind.CONSUMER)).isEqualTo(SPAN_KIND_CONSUMER); }