question: 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 ) ; }
target:  Registers a file type.