Error on "Read Fields" and "Loading Json Data" with "Get Server Response" since Jaspersoft Studio 6.13

[sebj]

Hy ! Since TIBCO Jaspersoft Studio 6.13 and more, the "Adapter Web Service" doesn't work.
6.8 and 6.12 are working
6.13 and last 6.20 are not working.

Error message with 6.13 :
java.lang.AbstractMethodError: com.jaspersoft.studio.data.webservice.WebServiceDescriptor.supportsGetFieldsOperation(Lcom/jaspersoft/studio/utils/jasper/JasperReportsConfiguration;Lnet/sf/jasperreports/engine/JRDataset;)Z
    at com.jaspersoft.studio.property.dataset.dialog.DataQueryAdapters.doGetFields(DataQueryAdapters.java:477)
    at com.jaspersoft.studio.data.designer.AQueryDesignerContainer$1.run(AQueryDesignerContainer.java:49)
    at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:122)

Error message with 6.20 :
java.lang.AbstractMethodError: Receiver class com.jaspersoft.studio.data.webservice.WebServiceDescriptor does not define or inherit an implementation of the resolved method 'abstract boolean supportsGetFieldsOperation(com.jaspersoft.studio.utils.jasper.JasperReportsConfiguration, net.sf.jasperreports.engine.JRDataset)' of interface com.jaspersoft.studio.data.fields.IFieldsProvider.
    at com.jaspersoft.studio.property.dataset.dialog.DataQueryAdapters.doGetFields(DataQueryAdapters.java:512)
    at com.jaspersoft.studio.data.designer.AQueryDesignerContainer$1.run(AQueryDesignerContainer.java:49)
    at org.eclipse.jface.operation.ModalContext$ModalContextThread.run(ModalContext.java:122)

 

With 6.13 and more, doesn't work :

 

 

With 6.12 and less, it's work :

[Al Bundy]

In Studio 6.13 it is at least still possible to map all Report-Fields manually, but only for XML-Requests

broken: JSON: Read-Fields-Button, Get-Server-Response-Button
       XML: Read-Fields-Button