Fix the issue where the service name is not checked for null when adding to the request header.

[hanbingleixue]

What type of PR is this?

Bug

What this PR does / why we need it?

Fix the issue where the service name is not checked for null when adding to the request header

Which issue(s) this PR fixes？

Fixes #1727

Does this PR introduce a user-facing change?

No

Checklist

• Make sure there is a GitHub_issue related with this PR before you start working on it.
• Make sure you have squashed your change to one single commit.
• GitHub Actions works fine in this PR.

[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 3 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...ant/flowcontrol/retry/FeignRequestInterceptor.java	50.00%	1 Missing and 1 partial ⚠️
...mant/flowcontrol/retry/HttpRequestInterceptor.java	75.00%	0 Missing and 1 partial ⚠️

Flag	Coverage Δ	Complexity Δ
unittests	42.67% <62.50%> (-0.01%)	181.00 <0.00> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ	Complexity Δ
...mant/flowcontrol/retry/HttpRequestInterceptor.java	42.70% <75.00%> (+0.15%)	0.00 <0.00> (ø)
...ant/flowcontrol/retry/FeignRequestInterceptor.java	37.30% <50.00%> (-0.61%)	0.00 <0.00> (ø)

... and 1 file with indirect coverage changes