code: @Override
      public String getPrincipalString(IAuthorizationPrincipal principal) {
          return getPrincipalString(principal.getType(), principal.getKey());
      }
docs: Returns the String used by an <code>IPermission</code> to represent an <code>
  IAuthorizationPrincipal</code>.
  
  @param principal org.apereo.portal.security.IAuthorizationPrincipal