code: public static Manifest readManifest(VirtualFile manifest) throws IOException {
          if (manifest == null) {
              throw MESSAGES.nullArgument("manifest file");
          }
          InputStream stream = new PaddedManifestStream(manifest.openStream());
          try {
              return new Manifest(stream);
          } finally {
              safeClose(stream);
          }
      }
docs: Read the manifest from given manifest VirtualFile.
  
  @param manifest the VF to read from
  @return JAR's manifest
  @throws IOException if problems while opening VF stream occur