presto-main/src/main/java/io/prestosql/operator/project/DictionaryAwarePageProjection.java/DictionaryAwarePageProjectionWork/getResult
class DictionaryAwarePageProjectionWork:        @Override
        public Block getResult()
        {
            if (produceLazyBlock) {
                return new LazyBlock(selectedPositions.size(), () -> {
                    setupDictionaryBlockProjection();
                    checkState(processInternal(), "processInternal() yielded");
                    checkState(result != null, "result has not been generated");
                    return result.getLoadedBlock();
                });
            }
            else {
                checkState(result != null, "result has not been generated");
                return result;
            }
        }