presto-main/src/main/java/io/prestosql/sql/planner/PlanFragment.java/PlanFragment/getJsonRepresentation
class PlanFragment:    @JsonProperty
    public Optional<String> getJsonRepresentation()
    {
        // @reviewer: I believe this should be a json raw value, but that would make this class have a different deserialization constructor.
        // workers don't need this, so that should be OK, but it's worth thinking about.
        return jsonRepresentation;
    }