code: function (oThis) {
                  if (!oThis.getOpener()) {
                      var sId = "";
                      if (oThis.oPopup) {
                          if (oThis.oPopup._oPosition.of instanceof sap.ui.core.Element) {
                              sId = oThis.oPopup._oPosition.of.getId();
                          } else {
                              if (oThis.oPopup._oPosition.of.length > 0) {
                                  sId = oThis.oPopup._oPosition.of[0].id;
                              } else {
                                  sId = oThis.oPopup._oPosition.of.id;
                              }
                          }
                      }
  
                      if (sId !== "") {
                          oThis.setAssociation("opener", sId, true);
                      } else {
                          Log.error("Neither an opener was set properly nor a corresponding one can be distinguished", "", "sap.ui.ux3.ToolPopup");
                      }
                  }
              }
docs: Checks if an opener was set. If not, this functions tries to get the opener from the Popup.
  
  @private