Merge pull request #225 from mulesoft/FlakyTestAjaxFunctionalTestCase

Flaky test AjaxFunctionalTestCase.testClientSubscribeWithString(cherry picked from commit c753fd9ffce9a1de246f6326abf0349ba14bf0cd)
(cherry picked from commit 0297a61aa9e194f6cd6c76e00ca2a45a5ee8d310)