code: public static String removePrefix(String principalName) {
  
          String result = principalName;
          if (CmsStringUtil.isNotEmptyOrWhitespaceOnly(principalName)) {
              if (hasPrefix(principalName)) {
                  result = principalName.trim().substring(I_CmsPrincipal.PRINCIPAL_GROUP.length() + 1);
              }
          }
          return result;
      }
docs: Removes the prefix if the given String starts with {@link I_CmsPrincipal#PRINCIPAL_GROUP} followed by a dot.<p>
  
  <ul>
  <li>Works if the given String is <code>null</code>.
  <li>If the given String does not start with {@link I_CmsPrincipal#PRINCIPAL_GROUP} followed by a dot it is returned unchanged.
  <li>Removes white spaces around the group name.
  <li>Also works with prefixes not being in upper case.
  <li>Does not check if the group after the prefix actually exists.
  </ul>
  
  @param principalName the group name to remove the prefix from
  
  @return the given String with the prefix {@link I_CmsPrincipal#PRINCIPAL_GROUP} with the following dot removed