Fix Nginx Collect validateParams function NPE

[Clownsw]

What's changed?

Fix Nginx Collect validateParams function NPE

Checklist

• I hereby agree to the terms of the HertzBeat CLA
• I have read the Contributing Guide
• I have written the necessary doc or comment.
• I have added the necessary unit tests and all cases have passed.

[a-little-fool]

Why did the previous one report a null pointer? I saw that nginxProtocol==null was used to determine first, so I don't think it will be reported. Perhaps I don't quite understand, and I would like to ask for your clarification

[Clownsw]

Why did the previous one report a null pointer? I saw that nginxProtocol==null was used to determine first, so I don't think it will be reported. Perhaps I don't quite understand, and I would like to ask for your clarification

 NginxProtocol nginxProtocol = metrics.getNginx(); // Here metrics have been used, So the following judgment has no effect
 if (metrics == null || nginxProtocol == null || nginxProtocol.isInValid()) {

[Clownsw]

Why did the previous one report a null pointer? I saw that nginxProtocol==null was used to determine first, so I don't think it will be reported. Perhaps I don't quite understand, and I would like to ask for your clarification

use old code test:

Metrics metrics = null;
NginxProtocol nginxProtocol = metrics.getNginx(); // NPE
if (metrics == null || nginxProtocol == null || nginxProtocol.isInValid()) {}

[Clownsw]

Why did the previous one report a null pointer? I saw that nginxProtocol==null was used to determine first, so I don't think it will be reported. Perhaps I don't quite understand, and I would like to ask for your clarification

 NginxProtocol nginxProtocol = metrics.getNginx(); // Here metrics have been used, So the following judgment has no effect
 if (metrics == null || nginxProtocol == null || nginxProtocol.isInValid()) {

use new code test:

Metrics metrics = null;
final NginxProtocol nginxProtocol;
if (metrics == null || (nginxProtocol = metrics.getNginx()) == null || nginxProtocol.isInValid()) {}
// Success

[a-little-fool]

为什么上一篇报空指针？我看到先用nginxProtocol==null来判断，所以我想不会报错。可能我不太明白，想请教您

 NginxProtocol nginxProtocol = metrics.getNginx(); // Here metrics have been used, So the following judgment has no effect
 if (metrics == null || nginxProtocol == null || nginxProtocol.isInValid()) {

使用新代码测试：

Metrics metrics = null;
final NginxProtocol nginxProtocol;
if (metrics == null || (nginxProtocol = metrics.getNginx()) == null || nginxProtocol.isInValid()) {}
// Success

I see, I didn't notice that. Thank you for pointing it out！LGTM！

[a-little-fool]

LGTM！