code: private String getParameterValue(CmsObject cms, Map<String, String[]> parameterMap, String key) {
  
          String result = null;
          String[] params = parameterMap.get(key);
          if ((params != null) && (params.length > 0)) {
              result = params[0];
          }
          if (result == null) {
              return "";
          }
          return result;
      }
docs: Returns the value of the given parameter name from a parameter map.<p>
  
  @param cms the current users context
  @param parameterMap the map containing the parameters
  @param key the parameter name
  @return the value of the parameter or an empty String