title: ZipException: ZIP file must have at least one entry in gradle build in android studio
body: <p>Importing an ancient eclipse android project of mine in android studio. Build fails with:</p>
  
  <pre class="lang-none prettyprint-override"><code>ImmutableJarInput{name=main, file=C:\Dropbox\eclipse_workspaces\_android_studio\monitoringModel\build\intermediates\transforms\mergeJavaRes\release\jars\2\3\main.jar, contentTypes=RESOURCES, scopes=PROJECT,PROJECT_LOCAL_DEPS, status=NOTCHANGED}
  ImmutableDirectoryInput{name=release, file=C:\Dropbox\eclipse_workspaces\_android_studio\monitoringModel\build\intermediates\classes\release, contentTypes=CLASSES, scopes=PROJECT, changedFiles={}}
  :monitoringModel:transformClassesAndResourcesWithSyncLibJarsForRelease FAILED
  
  FAILURE: Build failed with an exception.
  
  * What went wrong:
  Execution failed for task ':monitoringModel:transformClassesAndResourcesWithSyncLibJarsForRelease'.
  &gt; java.util.zip.ZipException: ZIP file must have at least one entry
  
  * Try:
  Run with --info or --debug option to get more log output.
  
  * Exception is:
  org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':monitoringModel:transformClassesAndResourcesWithSyncLibJarsForRelease'.
  ...
  Caused by: java.lang.RuntimeException: java.util.zip.ZipException: ZIP file must have at least one entry
  ...
  Caused by: java.util.zip.ZipException: ZIP file must have at least one entry
  </code></pre>
  
  <p>New to gradle - how should I debug this ?</p>