Added null checks

components/device-mgt/org.wso2.carbon.device.mgt.core/src/main/java/org/wso2/carbon/device/mgt/core/config/permission/PermissionManager.java

@@ -66,9 +66,12 @@ public class PermissionManager {
 				/* Un-marshaling Device Management configuration */
 				JAXBContext cdmContext = JAXBContext.newInstance(PermissionConfiguration.class);
 				Unmarshaller unmarshaller = cdmContext.createUnmarshaller();
-				PermissionConfiguration permissionConfiguration = (PermissionConfiguration) unmarshaller.unmarshal(permissionStream);
+				PermissionConfiguration permissionConfiguration = (PermissionConfiguration)
+						unmarshaller.unmarshal(permissionStream);
+				if((permissionConfiguration != null) && (permissionConfiguration.getPermissions() != null)){
 					this.addPermissions(permissionConfiguration.getPermissions());
 				}
+			}
 		} catch (JAXBException e) {
 			throw new DeviceManagementException("Error occurred while initializing Data Source config", e);
 		}