Webhooks plugin bundles a large number of libraries. Some of these can be provided by the platform (fugue). Others should be. There's 1.4MB totaly of jars hidden inside the webhooks plugin (though it normally expands the dependencies)
Http Client - we should be looking at whether we can use a bundled one, or bringing it into the platform such that we can use a bundled one. We don't have to worry about multiple version support in the webhooks plugin so there's nothing stopping us doing this work.