Codereview request: JDK-8044865 Fix raw and unchecked lint warnings in management-related code

[shanliang]

Hi,

Please review the following fix:
webrev: http://cr.openjdk.java.net/~sjiang/JDK-8044865/00/ 
<http://cr.openjdk.java.net/%7Esjiang/JDK-8044865/00/>
bug: https://bugs.openjdk.java.net/browse/JDK-8044865

Thanks,
Shanliang