RFR: JDK-8177107: Reduce memory footprint of java.lang.reflect.Constructor/Method

[Claes Redestad]

On Wed, 2 Mar 2022 20:28:45 GMT, Joe Darcy <darcy at openjdk.org> wrote:

> Refactoring of Method and Constructor to share a single empty array for parameters and exceptions as well as type variables.
> 
> Existing core reflection regression tests pass with the change.

src/java.base/share/classes/java/lang/reflect/Executable.java line 61:

> 59:     static final TypeVariable[] NO_TYPE_VARS = new TypeVariable[0];
> 60: 
> 61:     static final Class<?>[] NO_TYPES = new Class<?>[0];

Less concerning since it doesn't add extra classloading, but I note that we have similar constants in a few places, including `j.l.Class.EMPTY_CLASS_ARRAY` and `j.l.r.ProxyGenerator.EMPTY_CLASS_ARRAY`. Perhaps would make sense to consolidate these into a single place/instance (and use consistent names)

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PR: https://git.openjdk.java.net/jdk/pull/7667