SpanId { @Override public int hashCode() { return Objects.hashCode(spanId); } SpanId(long spanId); static SpanId invalid(); @Override boolean equals(Object obj); @Override int hashCode(); @Override String toString(); boolean isValid(); long getSpanId(); String getApiString();  }
@Test public void testHashCode() { assertThat(first.hashCode()).isEqualTo(first.hashCode()); assertThat(first.hashCode()).isNotEqualTo(second.hashCode()); }