Fix sporadic error in models provider junits

The sonar build of models fails once or twice a week in the junit for providers, with the following:
14:39:16 [INFO] Running org.onap.policy.models.provider.revisionhierarchy.HierarchyFetchTest*14:39:19* [ERROR] Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 3.25 s <<< FAILURE! - in org.onap.policy.models.provider.revisionhierarchy.HierarchyFetchTest*14:39:19* [ERROR] org.onap.policy.models.provider.revisionhierarchy.HierarchyFetchTest.testMultipleVersions Time elapsed: 3.246 s <<< FAILURE!14:39:19 java.lang.AssertionError: expected:<7> but was:<57>14:39:19 at org.onap.policy.models.provider.revisionhierarchy.HierarchyFetchTest.assertLatestDataTypesAreReturned(HierarchyFetchTest.java:278)14:39:19 at org.onap.policy.models.provider.revisionhierarchy.HierarchyFetchTest.testMultipleVersions(HierarchyFetchTest.java:76)14:39:19 14:39:20 [INFO] 14:39:20 [INFO] Results:14:39:20 [INFO] 14:39:20 [ERROR] Failures: 14:39:20 [ERROR] HierarchyFetchTest.testMultipleVersions:76->assertLatestDataTypesAreReturned:278 expected:<7> but was:<57>14:39:20 [INFO] 14:39:20 [ERROR] Tests run: 23, Failures: 1, Errors: 0, Skipped: 0