presto-spi/src/main/java/io/prestosql/spi/Page.java/Page/getRelatedDictionaryBlocks
class Page:    private Map<DictionaryId, DictionaryBlockIndexes> getRelatedDictionaryBlocks()
    {
        Map<DictionaryId, DictionaryBlockIndexes> relatedDictionaryBlocks = new HashMap<>();

        for (int i = 0; i < blocks.length; i++) {
            Block block = blocks[i];
            if (block instanceof DictionaryBlock) {
                DictionaryBlock dictionaryBlock = (DictionaryBlock) block;
                relatedDictionaryBlocks.computeIfAbsent(dictionaryBlock.getDictionarySourceId(), id -> new DictionaryBlockIndexes())
                        .addBlock(dictionaryBlock, i);
            }
        }
        return relatedDictionaryBlocks;
    }