Jasperreport with REST Web Service as the Dataset, the verb can't be null - jasper-reports

Question

Good day everyone!
I am trying to use Jasper Report with REST Web Service as my data adapter. I was able to preview the data, but I wasn't able to preview the report because it says that the verb can't be null.
here is the link to the source view of my jrxml (it's too long, so I can't post it here) :
RegisteredParticipants.jrxml
and this is my data adapter:
Everytime I try to preview the report, I get this error:
net.sf.jasperreports.engine.JRException: net.sf.jasperreports.engine.JRRuntimeException: net.sf.jasperreports.engine.JRException: Error creating request: net.sf.jasperreports.engine.JRException: The verb can't be null
at com.jaspersoft.studio.editor.preview.view.control.ReportControler.fillReport(ReportControler.java:545)
at com.jaspersoft.studio.editor.preview.view.control.ReportControler.access$20(ReportControler.java:520)
at com.jaspersoft.studio.editor.preview.view.control.ReportControler$5.run(ReportControler.java:401)
at org.eclipse.core.internal.jobs.Worker.run(Worker.java:55)
Caused by: net.sf.jasperreports.engine.JRRuntimeException: net.sf.jasperreports.engine.JRException: Error creating request: net.sf.jasperreports.engine.JRException: The verb can't be null
at net.sf.jasperreports.engine.fill.JRFillSubreport.prepare(JRFillSubreport.java:874)
at net.sf.jasperreports.components.table.fill.FillTableSubreport.prepareSubreport(FillTableSubreport.java:172)
at net.sf.jasperreports.components.table.fill.FillTable.prepare(FillTable.java:424)
at net.sf.jasperreports.engine.fill.JRFillComponentElement.prepare(JRFillComponentElement.java:152)
at net.sf.jasperreports.engine.fill.JRFillElementContainer.prepareElements(JRFillElementContainer.java:537)
at net.sf.jasperreports.engine.fill.JRFillBand.fill(JRFillBand.java:411)
at net.sf.jasperreports.engine.fill.JRFillBand.fill(JRFillBand.java:386)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillTitle(JRVerticalFiller.java:313)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReportStart(JRVerticalFiller.java:247)
at net.sf.jasperreports.engine.fill.JRVerticalFiller.fillReport(JRVerticalFiller.java:115)
at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:582)
at net.sf.jasperreports.engine.fill.BaseFillHandle$ReportFill.run(BaseFillHandle.java:123)
at java.lang.Thread.run(Thread.java:745)
Caused by: net.sf.jasperreports.engine.JRException: Error creating request: net.sf.jasperreports.engine.JRException: The verb can't be null
at com.jaspersoft.webservice.data.util.WebServiceConnector.createRequestForWs(WebServiceConnector.java:187)
at com.jaspersoft.webservice.data.util.WebServiceConnector.callWS(WebServiceConnector.java:134)
at com.jaspersoft.webservice.data.query.WebServiceQueryExecuter.createDatasource(WebServiceQueryExecuter.java:168)
at com.jaspersoft.webservice.data.query.WebServiceQueryExecuter.createDatasource(WebServiceQueryExecuter.java:1)
at net.sf.jasperreports.engine.fill.JRFillDataset.createQueryDatasource(JRFillDataset.java:1245)
at net.sf.jasperreports.engine.fill.JRFillDataset.initDatasource(JRFillDataset.java:723)
at net.sf.jasperreports.engine.fill.BaseReportFiller.setParameters(BaseReportFiller.java:438)
at net.sf.jasperreports.engine.fill.JRBaseFiller.fill(JRBaseFiller.java:550)
at net.sf.jasperreports.engine.fill.BaseReportFiller.fill(BaseReportFiller.java:396)
at net.sf.jasperreports.engine.fill.JRFillSubreport.fillSubreport(JRFillSubreport.java:732)
at net.sf.jasperreports.engine.fill.JRSubreportRunnable.run(JRSubreportRunnable.java:59)
at net.sf.jasperreports.engine.fill.AbstractThreadSubreportRunner.run(AbstractThreadSubreportRunner.java:221)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
... 1 more
Caused by: net.sf.jasperreports.engine.JRException: The verb can't be null
at com.jaspersoft.webservice.data.util.WebServiceConnector.createRequestForWs(WebServiceConnector.java:178)
... 14 more
I don't know if I missed anything and I don't have idea about the verbkey. I tried to connect the "RegisteredParticipantsRest" to the main dataset, but it didn't help . I hope someone can help me. Thanks!

Answer 1

I found out the cause of the error. I had to export the data adapter as xml, then set it as the "Default data adapater" on my "RegisteredParticipantsRest"