code: public Integer getImplementedVersion(Page page) {
          ContentEntityObject entityObject = getContentEntityManager().getById(page.getId());
          String value = getContentPropertyManager().getStringProperty(entityObject, IMPLEMENTED_VERSION);
          return value == null ? null : Integer.valueOf(value);
      }
docs: Retrieves the implemented version of the specification.
  
  @param page a {@link com.atlassian.confluence.pages.Page} object.
  @return the implemented version of the specification.