title: How to get contenthash of emitted assets in webpack plugin?
body: <p>Sometimes, for some reason, webpack emits assets with identical content. In the plugin I'm writing now, I need to make sure that the asset content has changed. I'm using <code>compiler.hooks.done</code> hook and <code>stats.compilation.emittedAssets</code> argument to determine emitted assets. To make sure that asset content has changed, I'm going to use contenthash.</p>
  <p>I've read the webpack documentation, but I can't figure out how  to get asset contenthash inside the plugin. Is this even possible? Does webpack calculates contenthash without additional tuning? Or do I have to calculate the asset hash on my own?</p>