Scroll end reached

I would like to know if there is a way to know, if scroll end is reached. So far i can't see anything quite like it. There is only `onScrollXChanged` and `onScrollYChanged` listeners. Other option for me is to get webview total inline content `height` and compare it to `onScrollYChanged` returned result.

首先检查插件中现有的 onScrollXChanged 和 onScrollYChanged 监听器，以了解滚动事件是如何公开的。确定如何公开滚动结束信号，然后验证消费者能否可靠地检测到 WebView 到达其内容末尾的时间。

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