Security-related types that are candidates to be FunctionalInterfaces in JDK 8

[Brian Goetz]

I'll just note that @FunctionalInterface is not *required* to convert a 
lambda to the target type; it is a statement of *design intent* by the 
interface author (which comes with some compile-time enforcement) that 
the interface is intended to be used to specify a function-like thing.


On 2/6/2013 2:43 PM, Joe Darcy wrote:
> Hi Sean,
>
> Apart from the performance concern Brian has already raised, I think the
> basic question to provide guidance on whether or not
> @FunctionalInterfaces should be applied to existing types is: do people
> routinely use anonymous inner classes to create instances of these types
> today?  If so, the @FunctionalInterface annotation should be added to
> indicate the type is meant to be used for lambda expressions too.
>
> The JSR for lambda has some specification material and there is a lambda
> faq in progress (http://www.lambdafaq.org/),  but I'm not aware of any
> existing discussion of the use of @FunctionalInterface since it is a
> relatively new addition to JDK 8 builds.
>
> HTH,
>
> -Joe
>
> On 2/6/2013 11:34 AM, Sean Mullan wrote:
>> I need to come up to speed on lambda in order to properly review this.
>> What's the best place to learn more about lambda and
>> FunctionalInterfaces?
>>
>> Thanks,
>> Sean
>>
>> On 02/05/2013 05:35 PM, Joe Darcy wrote:
>>> Hello,
>>>
>>> As part of Project Lambda, a FunctionalInterface annotation type was
>>> added to the platform to mark interfaces that are intended to be used in
>>> lambda expressions.  I've sent out a code review request to add this
>>> annotation to types in the core-libs area [1].
>>>
>>> To assist the security team in adding analogous annotations to your
>>> types, the list of candidate types in for security-related classes in
>>> java.* and javax.* is given below.  I recommend sub-tasks of JDK-8005297
>>> "Add FunctionalInterface support to the platform" be used to track the
>>> work of adding @FunctionalInterface annotations to security types.
>>>
>>> Thanks,
>>>
>>> -Joe
>>>
>>> [1]
>>> http://mail.openjdk.java.net/pipermail/core-libs-dev/2013-February/014292.html
>>>
>>>
>>>
>>> jdk/src/share/classes/java/security/DomainCombiner.java:81: Note:
>>> Candidate functional interface
>>> public interface DomainCombiner {
>>>         ^
>>> jdk/src/share/classes/java/security/KeyStore.java:212: Note: Candidate
>>> functional interface
>>>      public static interface LoadStoreParameter {
>>>                    ^
>>> jdk/src/share/classes/java/security/cert/CertPathParameters.java:40:
>>> Note: Candidate functional interface
>>> public interface CertPathParameters extends Cloneable {
>>>         ^
>>> jdk/src/share/classes/java/security/cert/CertPathValidatorResult.java:41:
>>> Note:
>>> Candidate functional interface
>>> public interface CertPathValidatorResult extends Cloneable {
>>>         ^
>>> jdk/src/share/classes/java/security/cert/CertStoreParameters.java:49:
>>> Note: Candidate functional interface
>>> public interface CertStoreParameters extends Cloneable {
>>>         ^
>>> jdk/src/share/classes/java/security/interfaces/ECKey.java:36: Note:
>>> Candidate functional interface
>>> public interface ECKey {
>>>         ^
>>> jdk/src/share/classes/java/security/interfaces/DSAKey.java:39: Note:
>>> Candidate functional interface
>>> public interface DSAKey {
>>>         ^
>>> jdk/src/share/classes/java/security/interfaces/RSAKey.java:41: Note:
>>> Candidate functional interface
>>> public interface RSAKey {
>>>         ^
>>> jdk/src/share/classes/java/security/PrivilegedAction.java:42: Note:
>>> Candidate functional interface
>>> public interface PrivilegedAction<T> {
>>>         ^
>>> jdk/src/share/classes/java/security/Guard.java:43: Note: Candidate
>>> functional interface
>>> public interface Guard {
>>>         ^
>>> jdk/src/share/classes/java/security/PrivilegedExceptionAction.java:45:
>>> Note: Candidate functional interface
>>> public interface PrivilegedExceptionAction<T> {
>>>         ^
>>> jdk/src/share/classes/java/security/Principal.java:39: Note: Candidate
>>> functional interface
>>> public interface Principal {
>>>         ^
>>> jdk/src/share/classes/java/security/spec/ECField.java:41: Note:
>>> Candidate functional interface
>>> public interface ECField {
>>>         ^
>>> jdk/src/share/classes/javax/crypto/interfaces/DHKey.java:40: Note:
>>> Candidate functional interface
>>> public interface DHKey {
>>>         ^
>>>
>>> jdk/src/share/classes/javax/security/auth/callback/CallbackHandler.java:68:
>>>
>>> Note: Candidate functional interface
>>> public interface CallbackHandler {
>>>         ^
>>>
>>
>