Builder resultBuilder(final Result.Builder resultBuilder) {
      this.resultBuilder = resultBuilder;
      return this;
    }
This ridiculous construction returns a true "null" when we have a value in error, resulting in
jackson not serializing it, or a wrapped reference of either null or the value, resulting in
jackson serializing a null if we don't have an error.

<p>This is done for binary compatibility: we need either an absent value, a present null value,
or a real value. And since Java Optionals refuse to hold nulls (by design) an atomic reference
is used instead.

@return the jackson optimized result
ethereum/api/src/main/java/org/hyperledger/besu/ethereum/api/jsonrpc/internal/results/tracing/flat/FlatTrace.java