code: public static Manifest getDefaultManifest()
          throws ArchiverException
      {
          try
          {
              String defManifest = "/org/codehaus/plexus/archiver/jar/defaultManifest.mf";
              InputStream in = Manifest.class.getResourceAsStream( defManifest );
              if ( in == null )
              {
                  throw new ArchiverException( "Could not find default manifest: " + defManifest );
              }
              try
              {
                  Manifest defaultManifest = new Manifest( new InputStreamReader( in, "UTF-8" ) );
                  defaultManifest.getMainAttributes().putValue( "Created-By", System.getProperty(
                      "java.vm.version" ) + " (" + System.getProperty( "java.vm.vendor" ) + ")" );
                  return defaultManifest;
              }
              catch ( UnsupportedEncodingException e )
              {
                  return new Manifest( new InputStreamReader( in ) );
              }
              finally
              {
                  IOUtil.close( in );
              }
          }
          catch ( ManifestException e )
          {
              throw new ArchiverException( "Default manifest is invalid !!", e );
          }
          catch ( IOException e )
          {
              throw new ArchiverException( "Unable to read default manifest", e );
          }
      }
docs: Construct a manifest from Ant's default manifest file.
  
  @return the default manifest.
  @throws ArchiverException if there is a problem loading the
  default manifest