NewCommentsConsumerTest#singleIssueCommentsTest fails intermitently

We randomly can get error like

org.apache.camel.component.jira.consumer.NewCommentsConsumerTest.singleIssueCommentsTest  Time elapsed: 1.939 s  <<< FAILURE!
java.lang.AssertionError: mock://result Received message count. Expected: <3> but was: <4>
	at org.apache.camel.component.mock.MockEndpoint.fail(MockEndpoint.java:1790)
	at org.apache.camel.component.mock.MockEndpoint.assertEquals(MockEndpoint.java:1767)

this is very rare to reproduce, but if we change the comments number from 3 to 3000 in this test, we can see this error constantly.

The problem comes from that the issue with comments can be read multiple times and send to the mock endpoint, we should ensure the issue with comments only be read once, just like the way in NewCommentsConsumerTest#multipleIssuesTest