JDK 14 RFR of JDK-8232442: Suppress warnings on non-serializable non-transient instance fields in java.management.*

[Joe Darcy]

Hello,

Quick background, ahead of strengthening javac's -Xlint:serial checks to 
include more aspects of a Serializable or Externalizable type ( 
JDK-8160675 ), I've been working through the JDK libraries to review 
issue found by the upcoming analysis (JDK-8231641).

The latest segment of the libraries to get this treatment is the 
java.management and java.management.rmi modules:

     JDK-8232442: Suppress warnings on non-serializable non-transient 
instance fields in java.management.*
     http://cr.openjdk.java.net/~darcy/8232442.0/

The forthcoming warnings were generally suppressed using

     @SuppressWarnings("serial")

paired with an explanatory comment. Common comments are

     // Not statically typed as Serializable

which states the cause of the general warning and

     // Conditionally serializable

which is used for collections or collection-like objects that are 
designed to be serializable if and only if their contents are.

An Externalizable class is required by the spec to have a no-arg 
constructor. Two Externalizable classes in this review do *not* have 
such a constructor. The classes have both been in the platform for many 
years and I just suppressed the warning rather than adding the constructors.

Thanks,

-Joe