code: public static void cleanup ()
    {
      // Reinitialize singletons to the default values
      if (LocaleCache.isInstantiated ())
        LocaleCache.getInstance ().reinitialize ();
      if (CountryCache.isInstantiated ())
        CountryCache.getInstance ().reinitialize ();
      if (LanguageCache.isInstantiated ())
        LanguageCache.getInstance ().reinitialize ();
      if (SerializationConverterRegistry.isInstantiated ())
        SerializationConverterRegistry.getInstance ().reinitialize ();
      if (MimeTypeDeterminator.isInstantiated ())
        MimeTypeDeterminator.getInstance ().reinitialize ();
      if (ThirdPartyModuleRegistry.isInstantiated ())
        ThirdPartyModuleRegistry.getInstance ().reinitialize ();
      if (TypeConverterRegistry.isInstantiated ())
        TypeConverterRegistry.getInstance ().reinitialize ();
      if (URLProtocolRegistry.isInstantiated ())
        URLProtocolRegistry.getInstance ().reinitialize ();
      if (EqualsImplementationRegistry.isInstantiated ())
        EqualsImplementationRegistry.getInstance ().reinitialize ();
      if (HashCodeImplementationRegistry.isInstantiated ())
        HashCodeImplementationRegistry.getInstance ().reinitialize ();
  
      // Clear caches
      if (DefaultTextResolver.isInstantiated ())
        DefaultTextResolver.getInstance ().clearCache ();
      EnumHelper.clearCache ();
      ResourceBundleHelper.clearCache ();
      if (RegExCache.isInstantiated ())
        RegExCache.getInstance ().clearCache ();
      CollatorHelper.clearCache ();
      LocaleHelper.clearCache ();
      StatisticsManager.clearCache ();
      SystemProperties.clearWarnedPropertyNames ();
      if (ImageDataManager.isInstantiated ())
        ImageDataManager.getInstance ().clearCache ();
  
      // Clean this one last as it is used in equals and hashCode implementations!
      ClassHierarchyCache.clearCache ();
    }
docs: Cleanup all custom caches contained in this library. Loaded SPI
  implementations are not affected by this method!