It is solved now. The transversal spec was changed by changing the
private static TraversalSpec getHostTraversalSpec() by public static TraversalSpec getHostSystemTraversalSpec() as shown below.
/**
*
* @return TraversalSpec specification to get to the HostSystem managed
* object.
*/
public static TraversalSpec getHostSystemTraversalSpec() {
// Create a traversal spec that starts from the 'root' objects
// and traverses the inventory tree to get to the Host system.
// Build the traversal specs bottoms up
SelectionSpec sSpec = new SelectionSpec();
sSpec.setName("VisitFolders");
// Traversal to get to the host from ComputeResource
TraversalSpec computeResourceToHostSystem = new TraversalSpec();
computeResourceToHostSystem.setName("computeResourceToHostSystem");
computeResourceToHostSystem.setType("ComputeResource");
computeResourceToHostSystem.setPath("host");
computeResourceToHostSystem.setSkip(false);
//computeResourceToHostSystem.setSelectSet(sSpecs);
computeResourceToHostSystem.getSelectSet().add(sSpec);
// Traversal to get to the hostFolder from DataCenter
TraversalSpec dataCenterToHostFolder = new TraversalSpec();
dataCenterToHostFolder.setName("DataCenterToHostFolder");
dataCenterToHostFolder.setType("Datacenter");
dataCenterToHostFolder.setPath("hostFolder");
dataCenterToHostFolder.setSkip(false);
//dataCenterToHostFolder.setSelectSet(sSpecs);
dataCenterToHostFolder.getSelectSet().add(sSpec);
// TraversalSpec to get to the DataCenter from rootFolder
TraversalSpec traversalSpec = new TraversalSpec();
traversalSpec.setName("VisitFolders");
traversalSpec.setType("Folder");
traversalSpec.setPath("childEntity");
traversalSpec.setSkip(false);
//SelectionSpec[] sSpecArr = new SelectionSpec[] { sSpec,
// dataCenterToHostFolder, computeResourceToHostSystem };
List<SelectionSpec> sSpecArr = new ArrayList<SelectionSpec>();
sSpecArr.add(sSpec);
sSpecArr.add(computeResourceToHostSystem);
sSpecArr.add(dataCenterToHostFolder);
//traversalSpec.setSelectSet(sSpecArr);
traversalSpec.getSelectSet().addAll(sSpecArr);
return traversalSpec;
}