PLF-5623 Failed to authenticate user with exo-jmx-client

Problem analysis:
* Wrong parameter for substring.
  It includes therefore the letter u and p for user name and password respectively.

Fix description:
* Update the index to get correctly the value of user name and password
Merge commit 'a75169f4b852d82066a4f1553e1c65a9a15727d4' into HEAD