code: public static SpanId fromBytes(byte[] src) {
      Utils.checkNotNull(src, "src");
      // TODO: Remove this extra condition.
      Utils.checkArgument(src.length == SIZE, "Invalid size: expected %s, got %s", SIZE, src.length);
      return fromBytes(src, 0);
    }
docs: Returns a {@code SpanId} built from a byte representation.
  
  @param src the representation of the {@code SpanId}.
  @return a {@code SpanId} whose representation is given by the {@code src} parameter.
  @throws NullPointerException if {@code src} is null.
  @throws IllegalArgumentException if {@code src.length} is not {@link SpanId#SIZE}.
  @since 0.5