private final boolean alphabetic;

    private final boolean digit;

    private final boolean letter;

    public CharTypeFilterFactory(final IndexSettings indexSettings, final Environment environment, final String name,
            final Settings settings) {
        super(indexSettings, name, settings);

        alphabetic = settings.getAsBoolean("alphabetic", true);

    // Compare to: "\u00c1".equalsIgnoreCase("\u00e1") == true
    assertFalse(Ascii.equalsIgnoreCase("\u00c1", "\u00e1"));
    // Test chars just outside the alphabetic range ('A'-1 vs 'a'-1, 'Z'+1 vs 'z'+1)
    assertFalse(Ascii.equalsIgnoreCase("@", "`"));
    assertFalse(Ascii.equalsIgnoreCase("[", "{"));
  }

  @GwtIncompatible // String.toUpperCase() has browser semantics

     * This method implements a time-based caching mechanism that refreshes the list
     * every 60 seconds to balance performance with up-to-date plugin discovery.
     *
     * @return array of data store names sorted alphabetically, never null
     */
    public synchronized String[] getDataStoreNames() {
        final long now = ComponentUtil.getSystemHelper().getCurrentTimeAsLong();
        if (now - lastLoadedTime > 60000L) {