How do I keep standard 'select all' and 'copy' menu items in the WebView text selection menu?

I need to extend android WebView's text selection menu with my custom commands. So far I have managed to implement my custom webview text selection menu the following way:

public class CustomActionWebView extends WebView {

    static String TAG = "CustomActionWebView";

    ActionMode mActionMode;

    int mMenuID;
    Activity mParentAct;

    ActionSelectListener mActionSelectListener;
    ButtonClickListener mButtonClick;

    public CustomActionWebView(Context context) {
        super(context);
    }

    public CustomActionWebView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public CustomActionWebView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    public void setActionMenu(int mActionMenu, Activity ParentAct) {

        setWebViewClient(new CustomWebViewClient());
        this.mMenuID = mActionMenu;
        mParentAct = ParentAct;
    }

    private ActionMode resolveActionMode(ActionMode actionMode) {
        if (actionMode != null) {
            final Menu menu = actionMode.getMenu();
            mActionMode = actionMode;
            menu.clear();

            mParentAct.getMenuInflater().inflate(mMenuID, menu);

            for (int i = 0; i < menu.size(); i++) {
                MenuItem mi = menu.getItem(i);

                mi.setOnMenuItemClickListener(item -> {
                    int id=item.getItemId();
                    if(id == R.id.cab_select_all)
                    {
                        String js = "var el =document.getElementsByTagName(\"BODY\")[0]; el.setSelectionRange(0, el.value.length); alert(el.value);)";
                        evaluateJavascript("javascript:" + js, null);
                    }
                    else getSelectedData( item.getItemId());
                    releaseAction();
                    return true;
                });

            }

        }
        mActionMode = actionMode;
        return actionMode;
    }

    @Override
    public ActionMode startActionMode(ActionMode.Callback callback) {
        ActionMode actionMode = super.startActionMode(callback);
        return resolveActionMode(actionMode);
    }

    @Override
    public ActionMode startActionMode(ActionMode.Callback callback, int type) {
        ActionMode actionMode = super.startActionMode(callback, type);
        return resolveActionMode(actionMode);
    }

    private void releaseAction() {
        if (mActionMode != null) {
            mActionMode.finish();
            mActionMode = null;
        }
    }

    private void getSelectedData(int menuID) {


        String js2 = "(function getSelectedText() {" +
                "var txt;" +
                "var parentID;" +
                "var test;" +
                "var menuID = " + menuID + ";" +
                "if (window.getSelection) {" +
                "txt = window.getSelection().toString();" +
                "parentID = window.getSelection().baseNode.parentNode.id;"+
                "test = '1st';"+
                "} else if (window.document.getSelection) {" +
                "txt = window.document.getSelection().toString();" +
                "parentID = window.document.getSelection().baseNode.parentNode.id;"+
                "test = '2nd';"+
                "} else if (window.document.selection) {" +
                "txt = window.document.selection.createRange().text;" +
                "parentID = window.document.selection.baseNode.parentNode.id;"+
                "test = '3rd';"+
                "}" +
                "JSInterface.callback(txt, menuID, parentID);" +
                "})()";


        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT) {
            evaluateJavascript("javascript:" + js2, null);
        } else {
            loadUrl("javascript:" + js2);
        }
    }

    public void linkJSInterface() {
        addJavascriptInterface(new ActionSelectInterface(this), "JSInterface");
        addJavascriptInterface(new ButtonClickInterface(this), "ButtonClick");
    }

    public void setActionSelectListener(ActionSelectListener actionSelectListener) {
        this.mActionSelectListener = actionSelectListener;
    }

    public void setVerseToolbarClickListener(ButtonClickListener mButtonClick) {
        this.mButtonClick = mButtonClick;
    }

    public void dismissAction() {
        releaseAction();
    }


    private class ActionSelectInterface {

        CustomActionWebView mContext;

        ActionSelectInterface(CustomActionWebView c) {
            mContext = c;
        }

        @JavascriptInterface
        public void callback(final String value, final int menuID, final String parentDivID) {
            if (mActionSelectListener != null) {
                mActionSelectListener.onTextSelectionMenuClick(menuID, value, parentDivID);
            }
        }

        @JavascriptInterface
        public void hl_click(long row_id) {
            if (mActionSelectListener != null) {
                mActionSelectListener.onHighlightClick(row_id);
            }
        }
    }

    private class ButtonClickInterface {

        CustomActionWebView mContext;

        ButtonClickInterface(CustomActionWebView c) {
            mContext = c;
        }

        @JavascriptInterface
        public void call(final String id) {
            if (mButtonClick != null) {
                mButtonClick.onClick(id);
            }
        }
    }


    private class CustomWebViewClient extends WebViewClient {

        private boolean mLastLoadFailed = false;

        @Override
        public void onPageFinished(WebView webView, String url) {
            super.onPageFinished(webView, url);
            if (!mLastLoadFailed) {
                CustomActionWebView customActionWebView = (CustomActionWebView) webView;
                customActionWebView.linkJSInterface();

            }
        }

        @Override
        public void onPageStarted(WebView webView, String url, Bitmap favicon) {
            super.onPageStarted(webView, url, favicon);
        }

        @Override
        public void onReceivedError(WebView view, WebResourceRequest request, WebResourceError error) {
            super.onReceivedError(view, request, error);
            mLastLoadFailed = true;
        }
    }


}

However this implementation results in the absence of the standard webview "COPY" and "SELECT ALL" menu items. I could implement my own COPY menu item, however I don't know how to have equivalent of the standard "SELECT ALL" menu item or to implement my own custom webview menu in such a way so that it preserves the standard ones. Can anyone please suggest how can I have "SELECT ALL" menu item working?

from How do I keep standard 'select all' and 'copy' menu items in the WebView text selection menu?