code: private String getPrefix() {
  
          if (m_prefix == null) {
              m_prefix = OpenCms.getSystemInfo().getContextPath()
                  + "/"
                  + OpenCms.getStaticExportManager().getProtectedExportPath()
                  + "/";
          }
          return m_prefix;
      }
docs: Returns the protected export path prefix.<p>
  
  @return the path prefix