How do I paste text with Android clipboard manager in an empty input in a WebView?

We have a web page with an input element on a webview App on Android.

If the input text is not empty, has text, you can touch and the clipboard manager is launched and shows:
When clipboard is empty “select all”
When clipboard is full “paste, select all”

BUT, when the input text is empty you can not launch the clipboard manager in order to paste text.

Should I implement onLongClick on Android webview app? if yes, what is the code to simply launch the Android Clipboard Manager?

Should I add an html paste button and solve it with html code?