presto-memory-context/src/main/java/io/prestosql/memory/context/RootAggregatedMemoryContext.java/RootAggregatedMemoryContext/RootAggregatedMemoryContext
class RootAggregatedMemoryContext:    RootAggregatedMemoryContext(MemoryReservationHandler reservationHandler, long guaranteedMemory)
    {
        this.reservationHandler = requireNonNull(reservationHandler, "reservationHandler is null");
        this.guaranteedMemory = guaranteedMemory;
    }