[Misc] Code hygiene

[kenliao94]

• Rewrote some for-loop for cleaner code.
• Removed one of the unused import.

[kenliao94]

There are a bunch of varying changes here. Not sure it makes sense as a single commit. Perhaps the iteration Java-language updates go as one easy commit.

I do not see a reason to remove null checks.

Is this PR part of a JIRA or NO-JIRA change?

This is part of a NO-JIRA change. I am just trying to clean up the code as I navigate the code :) I moved the removing redundant null checks from this PR to another I will create later to make this PR more about trivial updates.

[kenliao94]

Hey Matt and JB, are there any more concerns about this PR? I checked the Jenkins failing tests they are about KahaDB

[INFO] ActiveMQ ........................................... SUCCESS [ 0.852 s]

[INFO] ActiveMQ :: BOM .................................... SUCCESS [ 0.248 s]

[INFO] ActiveMQ :: Openwire Generator ..................... SUCCESS [ 1.091 s]

[INFO] ActiveMQ :: Client ................................. SUCCESS [02:50 min]

[INFO] ActiveMQ :: Openwire Legacy Support ................ SUCCESS [ 2.411 s]

[INFO] ActiveMQ :: JAAS ................................... SUCCESS [01:46 min]

[INFO] ActiveMQ :: Broker ................................. SUCCESS [01:18 min]

[INFO] ActiveMQ :: KahaDB Store ........................... FAILURE [ 03:30 h]

And the broker tests passed.

[jbonofre]

I did a new pass and it looks good to me. If @mattrpav is OK (as he requested a change), I will merge it.