increase code coverage of notification-core to 80%

notification-core/pom.xml

...roup/osdu/notification/api/GlobalErrorControllerTest.java

...g/opengroup/osdu/notification/api/PubsubEndpointTest.java

...group/osdu/notification/auth/factory/AuthFactoryTest.java

...p/osdu/notification/di/CredentialHeadersProviderTest.java

...rg/opengroup/osdu/notification/di/RequestInfoExtTest.java

...up/osdu/notification/di/SubscriptionCacheFactoryTest.java

...p/osdu/notification/errors/SpringExceptionMapperTest.java

...roup/osdu/notification/logging/ResponseLogFilterTest.java

...up/osdu/notification/service/NotificationHandlerTest.java

...up/osdu/notification/service/SubscriptionHandlerTest.java

...engroup/osdu/notification/swagger/HomeControllerTest.java

...group/osdu/notification/utils/NotificationFilterTest.java