code: public String getProxyRemoteAddr(String realIpHeader) {
          String ip = null;
          if (realIpHeader != null && realIpHeader.length() != 0) {
              ip = getHeaderString(realIpHeader);
          }
          if (StringUtils.isBlank(ip)) {
              ip = getHeaderString("X-Real-IP");
              if (StringUtils.isBlank(ip) || "unknown".equalsIgnoreCase(ip)) {
                  ip = getHeaderString("X-Forwarded-For");
                  if (StringUtils.isNotBlank(ip) && !"unknown".equalsIgnoreCase(ip)) {
                      ip = ip.split(",")[0];
                  }
              }
              if (StringUtils.isBlank(ip) || "unknown".equalsIgnoreCase(ip)) {
                  ip = getHeaderString("Proxy-Client-IP");
              }
              if (StringUtils.isBlank(ip) || "unknown".equalsIgnoreCase(ip)) {
                  ip = getHeaderString("WL-Proxy-Client-IP");
              }
              if (StringUtils.isNotBlank(ip)) {
                  ip = ip.toLowerCase();
              }
          }
          return ip;
      }
docs: <p>getProxyRemoteAddr.</p>
  
  @param realIpHeader a {@link java.lang.String} object.
  @return a {@link java.lang.String} object.