How to use the azure-kusto-ingest.IngestionDescriptors function in azure-kusto-ingest

const IngestClient = require("azure-kusto-ingest").IngestClient;
const IngestStatusQueues = require("azure-kusto-ingest").IngestStatusQueues;
const IngestionProps = require("azure-kusto-ingest").IngestionProperties;
const { ReportLevel, ReportMethod } = require("azure-kusto-ingest").IngestionPropertiesEnums;
const KustoConnectionStringBuilder = require("azure-kusto-data").KustoConnectionStringBuilder;
const { DataFormat, JsonColumnMapping , IngestionMappingType} = require("azure-kusto-ingest").IngestionPropertiesEnums;
const { BlobDescriptor } = require("azure-kusto-ingest").IngestionDescriptors;

const clusterName = null;
const appId = null;
const appKey = null;
const authorityId = null;

const props = new IngestionProps({
    database: "Database",
    table: "Table",
    format: DataFormat.JSON,
    ingestionMapping : [
        new JsonColumnMapping("TargetColumn1", "$.sourceProp1"),
        new JsonColumnMapping("TargetColumn2", "$.sourceProp2"),
        new JsonColumnMapping("TargetColumn3", "$.sourceProp3")
    ],
    ingestionMappingType: IngestionMappingType.JSON,