code: public synchronized Definition addOverride(Class<?> clazz, TextColor foreground, TextColor background, SGR... styles) {
          Definition definition = new Definition(new Style(foreground, background, styles));
          overrideDefinitions.put(clazz, definition);
          return definition;
      }
docs: Adds an override for a particular class, or overwrites a previously defined override.
  @param clazz Class to override the theme for
  @param foreground Color to use as the foreground color for this override style
  @param background Color to use as the background color for this override style
  @param styles SGR styles to apply for this override
  @return The newly created {@link Definition} that corresponds to this override.