code: Map<String, CssProperty> getCssPropertiesAsMap(final boolean rebuild) {
          if (rebuild || !loadedOnce) {
              synchronized (cssProperties) {
                  if (rebuild || !loadedOnce) {
                      cssProperties.clear();
                      load(cssProperties);
                      loadedOnce = true;
                      setModified(true);
                  }
              }
          }
          return cssPropertiesAsMap;
      }
docs: rebuild true to rebuild, the load method will be invoked again.
  
  @return the cssProperties as map with key as the cssName and value as
  {@code CssProperty}.
  @since 1.0.0
  @author WFF