Flaky JUnit Tests identified in apollo-configservice.

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Describe the bug
In the course of test execution, the testAppNamespace within AppNamespaceServiceWithCacheTest advances to a point at line 197 in AppNamespaceServiceWithCache.
apollo/apollo-configservice/src/main/java/com/ctrip/framework/apollo/configservice/service/AppNamespaceServiceWithCache.java

List ids = Lists.newArrayList(appNamespaceIdCache.keySet());

Here, it retrieves a set of keys, generating a hash result from the following that appears to be nondeterministic. The same hash in line 201 is partition divides the array into subarrays of a given size. When the order changes we can expect different subarrays.
I found and confirmed the flaky behavior using an open-source research tool NonDex, which shuffles implementations of nondeterminism operations.

To Reproduce
Steps to reproduce the behavior:

1. Run the following command

mvn edu.illinois:nondex-maven-plugin:2.1.1:nondex -pl apollo-configservice -Dtest=com.ctrip.framework.apollo.configservice.service.AppNamespaceServiceWithCacheTest#testAppNamespace

Expected behavior
The testcase should pass everytime

Additional Details & Logs

Test Environment:

openjdk version "1.8.0_351"
Apache Maven 3.6.3
Operating System: macOS
Product Version: 13.5.2