Set local resource CSEBase parentID to empty string in order for codec to set it up to NULL

LibOneM2M/OneM2M_Functions.ttcn

@@ -1953,7 +1953,7 @@ module OneM2M_Functions {
 					v_myResource.cSEBase.resourceName := PX_CSE1_NAME;
 					v_myResource.cSEBase.resourceType := p_resourceType;
 					v_myResource.cSEBase.resourceID := f_resourceIdCleaner(PX_CSE1_ID);
-					v_myResource.cSEBase.parentID := omit;		//Following TS-0001, it must be NULL
+					v_myResource.cSEBase.parentID := "";//Following TS-0001, it must be NULL. Set to a value for Codec to set it to null
 					v_myResource.cSEBase.creationTime := fx_generateTimestamp();
 					v_myResource.cSEBase.creationTime := "20171231T012345";
 					v_myResource.cSEBase.lastModifiedTime := v_myResource.cSEBase.creationTime;