presto-parquet/src/main/java/io/prestosql/parquet/reader/LongColumnReader.java/LongColumnReader/readValue
class LongColumnReader:    @Override
    protected void readValue(BlockBuilder blockBuilder, Type type)
    {
        if (definitionLevel == columnDescriptor.getMaxDefinitionLevel()) {
            type.writeLong(blockBuilder, valuesReader.readLong());
        }
        else if (isValueNull()) {
            blockBuilder.appendNull();
        }
    }