Replaced HashSet with LinkedHashSet for deterministic ordering in IsIn

[mumbler6]

The indeterministic ordering of a HashSet in the IsIn class causes the ordering of objects when serialized (to a JSON string) to be inconsistent sometimes. The following test case fails if this happens:

koryphe/core/src/test/java/uk/gov/gchq/koryphe/impl/predicate/IsInTest.java

Line 53 in 36c63c3

public void shouldJsonSerialiseAndDeserialise() throws IOException {

This PR proposes to replace the HashSet in the IsIn class with a LinkedHashSet, maintaining insertion order so that the test case is correct. It didn't make sense to me to simply change the test case, since the test case is testing serialization of the IsIn class and is comparing two JSON strings, which cannot be sorted or really manipulated.

This change was confirmed by running the NonDex tool, which explores and reports errors in different behaviors of under-determined Java APIs.

To reproduce this problem, you can run the test with NonDex using these commands:

mvn install -pl core -am -DskipTests

mvn -pl core edu.illinois:nondex-maven-plugin:2.1.7:nondex -Dtest=uk.gov.gchq.koryphe.impl.predicate.IsInTest#shouldJsonSerialiseAndDeserialise

Here are screenshots of the output produced by NonDex before and after the fix:

Please let me know if you want to discuss these changes.

[CLAassistant]

All committers have signed the CLA.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud