presto-parquet/src/main/java/io/prestosql/parquet/ParquetTypeUtils.java/ParquetTypeUtils/getDescriptors
class ParquetTypeUtils:    public static Map<List<String>, RichColumnDescriptor> getDescriptors(MessageType fileSchema, MessageType requestedSchema)
    {
        Map<List<String>, RichColumnDescriptor> descriptorsByPath = new HashMap<>();
        List<PrimitiveColumnIO> columns = getColumns(fileSchema, requestedSchema);
        for (String[] paths : fileSchema.getPaths()) {
            List<String> columnPath = Arrays.asList(paths);
            getDescriptor(columns, columnPath)
                    .ifPresent(richColumnDescriptor -> descriptorsByPath.put(columnPath, richColumnDescriptor));
        }
        return descriptorsByPath;
    }