presto-spi/src/main/java/io/prestosql/spi/block/MapBlockBuilder.java/MapBlockBuilder/getRetainedSizeInBytes
class MapBlockBuilder:    @Override
    public long getRetainedSizeInBytes()
    {
        long size = INSTANCE_SIZE
                + keyBlockBuilder.getRetainedSizeInBytes()
                + valueBlockBuilder.getRetainedSizeInBytes()
                + sizeOf(offsets)
                + sizeOf(mapIsNull)
                + hashTables.getRetainedSizeInBytes();
        if (blockBuilderStatus != null) {
            size += BlockBuilderStatus.INSTANCE_SIZE;
        }
        return size;
    }