I ran the sample adwords.axis.v201809.reporting.DownloadCriteriaReportWithAwql.
Its produced log:"[02 七月 2020 19:12:22,396-report_download:INFO:main] Request made: Service: reportdownload Method: POST clientCustomerId: 867-938-4437 URL: https://adwords.google.com//api/adwords/reportdownload/v201809 Request ID: null ResponseTime(ms): null OperationsCount: null IsFault: false FaultMessage: null"
And the csv file downloaded is an empty file with title only.
This can happen if you don't have any campaigns which support criteria performance report. A common case of this is App Campaigns, see the linked document for details of which reports are supported.
I ran the sample adwords.axis.v201809.reporting.DownloadCriteriaReportWithAwql. Its produced log:"[02 七月 2020 19:12:22,396-report_download:INFO:main] Request made: Service: reportdownload Method: POST clientCustomerId: 867-938-4437 URL: https://adwords.google.com//api/adwords/reportdownload/v201809 Request ID: null ResponseTime(ms): null OperationsCount: null IsFault: false FaultMessage: null" And the csv file downloaded is an empty file with title only.