presto-spi/src/main/java/io/prestosql/spi/memory/MemoryAllocation.java/MemoryAllocation/MemoryAllocation
class MemoryAllocation:    @JsonCreator
    public MemoryAllocation(
            @JsonProperty("tag") String tag,
            @JsonProperty("allocation") long allocation)
    {
        this.tag = requireNonNull(tag, "tag is null");
        this.allocation = allocation;
    }