Ja, es ist möglich. So mache ich es in JasperReports Server v6.2.1 mit dem jrs-rest-java-client v6.2.3:
// build configuration object
RestClientConfiguration configuration = new RestClientConfiguration("http://localhost:8080/jasperserver");
configuration.setContentMimeType(MimeType.JSON);
configuration.setAcceptMimeType(MimeType.JSON);
configuration.setAuthenticationType(AuthenticationType.SPRING);
configuration.setLogHttp(true);
configuration.setLogHttpEntity(true);
// build client and authenticate
JasperserverRestClient client = new JasperserverRestClient(configuration);
Session session = client.authenticate("jasperadmin", "jasperadmin");
String reportUnitUri = "/path/to/reportUnit";
// first get the version of the reportUnit to prevent update conflicts from optimistic locking
OperationResult<ClientReportUnit> reportUnitOperationResult = session.resourcesService().resource(reportUnitUri).get(ClientReportUnit.class);
Integer reportUnitVersion = reportUnitOperationResult.getEntity().getVersion();
// build patchDescriptor with the dataSource field
PatchDescriptor patchDescriptor = new PatchDescriptor();
patchDescriptor.setVersion(reportUnitVersion);
patchDescriptor.field("dataSource", "/path/to/repository/dataSource");
// apply the patchDescriptor
session.resourcesService().resource(reportUnitUri).patchResource(ClientReportUnit.class, patchDescriptor);