code: public Locale getMainLocale() {
  
          if (m_mainLocale != null) {
              return m_mainLocale;
          }
          try {
              CmsLocaleGroup localeGroup = m_cms.getLocaleGroupService().readLocaleGroup(this);
              m_mainLocale = localeGroup.getMainLocale();
              return m_mainLocale;
          } catch (CmsException e) {
              return null;
          }
      }
docs: Returns the main locale for this resource.<p>
  
  @return the main locale for this resource