Fix Server-example Unknown user

[Pan-YuJie]

Fix Server-example Unknown user

Changes proposed in this pull request:

Check mailbox configuration when submitting. Contributor Guide

[codecov]

Codecov Report

Patch coverage has no change and project coverage change: -0.02% ⚠️

Comparison is base (2b11fac) 34.56% compared to head (a163d7f) 34.54%.
Report is 2 commits behind head on develop.

❗ Current head a163d7f differs from pull request most recent head 4a374ae. Consider uploading reports for the commit 4a374ae to get more accurate results

Additional details and impacted files

@@              Coverage Diff              @@
##             develop    #1446      +/-   ##
=============================================
- Coverage      34.56%   34.54%   -0.02%     
  Complexity       847      847              
=============================================
  Files            262      262              
  Lines           5896     5899       +3     
  Branches         547      547              
=============================================
  Hits            2038     2038              
- Misses          3665     3668       +3     
  Partials         193      193              

Files Changed	Coverage Δ
.../hippo4j/core/enable/BeforeCheckConfiguration.java	0.00% <0.00%> (ø)
...ain/java/cn/hippo4j/auth/security/AuthManager.java	0.00% <0.00%> (ø)
...po4j/auth/service/impl/UserDetailsServiceImpl.java	0.00% <ø> (ø)

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