JDK 8 code review request for 7007535: (reflect) Please generalize Constructor and Method

[joe.darcy at oracle.com]

Hello.

Please code review my JDK 8 changes for

    7007535: (reflect) Please generalize Constructor and Method
    http://cr.openjdk.java.net/~darcy/7007535.3

To summarize the changes, a new superclass is defined to capture the 
common functionality of java.lang.reflect.Method and 
java.lang.reflect.Constructor.  That superclass is named "Executable" 
along the lines of javax.lang.model.ExecutableElement, which models 
constructors and methods in the JSR 269 language model.

Both specification and implementation code are shared.  To preserve the 
right @since behavior, it is common that in Method/Constructor the 
javadoc for a method will now look like:

/**
 * {@inheritDoc}
 * @since 1.5
 */

Since Executable is being created in JDK 8, it would be incorrect for 
methods in that class to have an @since of 1.5; adding the @since in 
Method/Constructor preserves the right information.

It would have been natural to also move common fields to Executable; 
however, HotSpot treats the Constructor and Method type specially and 
relies on the existing field ordering.  Since altering the field layout 
would require coordinated HotSpot changes, I'm opting to not perform 
such a change right now.  At least one abstract accessor method is 
declared in Executable to still allow code sharing even though the 
required field is not present.  In other cases, package private instance 
methods on Executable are passed the needed state from overridden public 
methods in Method/Constructor.

All java/lang/reflect regression tests pass on a full build with these 
changes.

Thanks,

-Joe