When you set the buffer size to 1 it's rejected with the message below.
That seems wrong: I understand value 0 is meaningless but 1 doesn't sound irrelevant.
The FetchingEventRelay javadoc says (8 parameters constructor):
"IllegalArgumentException - if bufferSize or maxNotifs is less than 1"

java.lang.IllegalArgumentException: The bufferSize cannot be less than 1, no meaning.
at javax.management.event.FetchingEventRelay.<init>(FetchingEventRelay.java:197)
at javasoft.sqe.jmx.test.functional.EventClientTest10.run(EventClientTest10.java:95)
at javasoft.sqe.jmx.share.TestStarter.<init>(TestStarter.java:28)
at javasoft.sqe.jmx.share.TestStarter.main(TestStarter.java:79)