code: private String getValue(FilterConfig filterConfig, String initParam, String variable) {
          final String value = filterConfig.getInitParameter(initParam);
          if (StringUtils.isNotBlank(value)) {
              return value;
          } else {
              return variable;
          }
      }
docs: Returns the value of the initParam.
  @param filterConfig a FilterConfig instance
  @param initParam the name of the init parameter
  @param variable the variable to use if the init param was not defined
  @return a String