[bluetooth] Cleanup

[lsiepel]

Some minor cleanup of warnings, code analysis / performance.
No functional change

[lolodomo]

LGTM

[dw-8]

@lsiepel
Can you advise why you reverted #15320 that partially reverted #13967 to fix issue #15313.

Changing:
for (int i = 0; i < value.length; i++) {
ret[i] = value[i];
}

To:
System.arraycopy(value, 0, ret, 0, value.length);

Caused:
java.lang.ArrayStoreException: arraycopy: type mismatch: can not copy byte[] into int[]
at java.lang.System.arraycopy(Native Method) ~[?:?]

[lsiepel]

You are right, it hsould not have been added to that PR. Somehow i forgot and fixed the SAT warning with the same implementation leading to the same ArrayStoreException
I still have to get used to how this is treated in java. No build exception. I really like how c# handles this. Nevertheless i'll come up with a solution asap.