Running integration tests throws unsupported operation exception in grails 2.2?

I am using grails 2.2 for development. I am running integration tests with test-app -integration command. 

I have lots of integration tests but the display shows only a few tests are being run and i get few initialization error exceptions in console. What is the reason for this same error being thrown every now and then?

|Running 68 integration tests... 8 of 50
--Output from testGetNumbersAfterInRange--

|Running 68 integration tests... 9 of 50
--Output from initializationError--
Failure: |
initializationError(BillingServiceTests)
|
java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableCollection.add(Collections.java:1075)

java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableCollection.add(Collections.java:1075)

|Running 68 integration tests... 10 of 50
--Output from initializationError--
Failure: |
initializationError(CompositeEventControllerTests)
|
java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableCollection.add(Collections.java:1075)

java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableCollection.add(Collections.java:1075)

|Running 68 integration tests... 11 of 50
--Output from initializationError--
Failure: |
initializationError(CompositeEventControllerTransactionalTests)
|
java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableCollection.add(Collections.java:1075)

java.lang.UnsupportedOperationException
at java.util.Collections$UnmodifiableCollection.add(Collections.java:1075)