Fix for data structure concurrentHashmap which results in flaky-tests

[219sansim]

Overview:
Change concurrentHashMap to Collections.synchronizedMap(new HashMap<>()) as it results in flaky tests for the test com.cerner.common.kafka.consumer.ProcessingKafkaConsumerTest.nextRecord_fairProcessing

Command to reproduce:
mvn -pl common-kafka edu.illinois:nondex-maven-plugin:2.1.1:nondex -Dtest=com.cerner.common.kafka.consumer.ProcessingKafkaConsumerTest#nextRecord_fairProcessing

Result:
The test fails on 4/5 iterations of the Nondex tool

Reason:
According to concurrentHashMap documentation,
"Because the elements of a ConcurrentHashMap are not ordered in any particular way, and may be processed in different orders in different parallel executions, the correctness of supplied functions should not depend on any ordering"

About the tool used to detect the Error:
This test is detected as flaky by the NonDex tool developed by researchers at UIUC.
Flaky tests are tests in software development that produce inconsistent or unreliable results, which can lead to false non-deterministic outcomes of the test case, fixing them is important to both reliable testing and fixing vulnerabilities in the code.

[bjchris32]

Could you explain why you modified CUT instead of modifying the test to make the assertions pass?
I think it would be better to just modify the assertions, so that it would not affect the original use cases, such as performance in the program.

[219sansim]

The test depends heavily on ordering and in effect it would be checking nothing (it would destroy the complete logic, in effect we would have to delete the test), we would need to modify code under test