public final void registerFileType(@NotNull FileType type,@NonNls @Nullable String... defaultAssociatedExtensions){
  List<FileNameMatcher> matchers=new ArrayList<FileNameMatcher>();
  if (defaultAssociatedExtensions != null) {
    for (    String extension : defaultAssociatedExtensions) {
      matchers.add(new ExtensionFileNameMatcher(extension));
    }
  }
  registerFileType(type,matchers);
}

public final void registerFileType ( @ NotNull FileType type , @ NonNls @ Nullable String ... defaultAssociatedExtensions ) { List < FileNameMatcher > matchers = new ArrayList < FileNameMatcher > ( ) ; if ( defaultAssociatedExtensions != null ) { for ( String extension : defaultAssociatedExtensions ) { matchers . add ( new ExtensionFileNameMatcher ( extension ) ) ; } } registerFileType ( type , matchers ) ; }
registers a file type .
