presto-parquet/src/main/java/io/prestosql/parquet/predicate/PredicateUtils.java/PredicateUtils/getStatistics
class PredicateUtils:    private static Map<ColumnDescriptor, Statistics<?>> getStatistics(BlockMetaData blockMetadata, Map<List<String>, RichColumnDescriptor> descriptorsByPath)
    {
        ImmutableMap.Builder<ColumnDescriptor, Statistics<?>> statistics = ImmutableMap.builder();
        for (ColumnChunkMetaData columnMetaData : blockMetadata.getColumns()) {
            Statistics<?> columnStatistics = columnMetaData.getStatistics();
            if (columnStatistics != null) {
                RichColumnDescriptor descriptor = descriptorsByPath.get(Arrays.asList(columnMetaData.getPath().toArray()));
                if (descriptor != null) {
                    statistics.put(descriptor, columnStatistics);
                }
            }
        }
        return statistics.build();
    }