presto-spi/src/main/java/io/prestosql/spi/block/MapBlock.java/MapBlock/getRetainedSizeInBytes
class MapBlock:    @Override
    public long getRetainedSizeInBytes()
    {
        return retainedSizeInBytes + keyBlock.getRetainedSizeInBytes() + valueBlock.getRetainedSizeInBytes() + hashTables.getRetainedSizeInBytes();
    }