feat:support namespace exports configuration if not created.

[SkyeBeFreeman]

PR Type

Describe what this PR does for and how you did.

Adding the issue link (#xxx) if possible.

Note

Checklist

• Add information of this PR to CHANGELOG.md in root of project.
• Add documentation in javadoc or comment below the PR if necessary.

[codecov]

Codecov Report

Attention: Patch coverage is 70.83333% with 7 lines in your changes missing coverage. Please review.

Project coverage is 67.01%. Comparing base (6f881b0) to head (ca9b74b).
Report is 2 commits behind head on 2021.

Files with missing lines	Patch %	Lines
...mmon/spi/impl/DefaultInstanceMetadataProvider.java	70.00%	1 Missing and 2 partials ⚠️
...aris/registry/NamespaceRegistrationCustomizer.java	71.42%	1 Missing and 1 partial ⚠️
...config/PolarisContextEnvironmentPostProcessor.java	33.33%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               2021    #1611      +/-   ##
============================================
- Coverage     67.02%   67.01%   -0.02%     
  Complexity       20       20              
============================================
  Files           340      341       +1     
  Lines          8298     8318      +20     
  Branches       1028     1032       +4     
============================================
+ Hits           5562     5574      +12     
- Misses         2249     2252       +3     
- Partials        487      492       +5     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[shedfreewu]

ok