code: private static String extractPathInfo(String pPathInfo, ProcessingParameters pProcessingParams) {
          String pathInfo = pPathInfo;
  
          // If no pathinfo is given directly, we look for a query parameter named 'p'.
          // This variant is helpful, if there are problems with the server mangling
          // up the pathinfo (e.g. for security concerns, often '/','\',';' and other are not
          // allowed in encoded form within the pathinfo)
          if (pProcessingParams != null && (pPathInfo == null || pPathInfo.length() == 0 || pathInfo.matches("^/+$"))) {
              pathInfo = pProcessingParams.getPathInfo();
          }
          return normalizePathInfo(pathInfo);
      }
docs: Extract path info either from the 'real' URL path, or from an request parameter