title: Gradle: Exclude file from Android assets folder
body: <p>Please, do you know a way how to exclude some file from Android project assets folder before  multiple assets folders are merged or during the merge?</p>
  
  <p>For example:</p>
  
  <pre><code>android {
    sourceSets {
      main {
        assets.srcDirs = [fileTree(dir: 'assets1', exclude: 'myfile.txt'), 'assets2'] // does not work
        assets.exclude 'assets1/myfile.txt' // does not work
        assets.exclude '**/*.txt' // does not work
        assets.exclude '*.txt' // does not work
      }
    }
  
    packagingOptions {
      exclude 'assets1/myfile.txt' // does not work
      exclude '**/*.txt' // does not work
      exclude '*.txt' // does not work either
    }
  
  
    aaptOptions {
      ignoreAssetsPattern "myfile.txt" // does not work
    }
  }
  </code></pre>