Incubation Feature Clarifications

[Brian Goetz]

Part of the goal of the Incubating JEP is to make the 
incubation-vs-permanent difference as small as possible.  For almost 
anything not explicitly spelled out in the JEP, the answer is usually 
"no different than any other feature."  In that light:

> Hi,
>   I am Manoj from the Eclipse Java Development Tools (JDT) and from Eclipse
> JDT Dev, we have a couple of clarifications regarding the incubation
> features:
>
>      Mandatory or Optional: We understand that when an incubation feature is
>     included in a release, it should be of production quality. However, do
>     we, as spec/compiler implementers have the freedom to omit an incubation
>     feature? In Other words, would we be termed non-compliant if we do not
>     implement a particular incubation feature?

This one is spelled out in the JEP, but the answer is: no different than 
any other feature.  It's part of the spec, so its part of what the 
ecosystem should support.  (This further underscores the fact that 
incubating features are not for experimental or risky features.)

>      Timeline:  How much minimum time (in weeks/months) before the release
>     can we expect a feature to be categorized as incubation? If it depends
>     on the feature, what could be a ballpark estimate?
>

No different than any other feature.  For any feature, incubating or 
not, the key milestone is Propose To Target; at this point, a JEP owner 
should consider whether including such a feature at this point in the 
cycle is the best choice.  (Incubating or not, integrating a risky 
feature near the close of the development cycle is not a good idea; 
there's another train coming soon.)

JEPs that affect the platform specification are tagged as Scope: SE.  
Language features are tracked in component specification:language; VM 
features in specification:vm.  It is easy to create queries that track 
JEPs by filtering on these fields; this dashboard, used by the SE 10 EG 
(https://bugs.openjdk.java.net/secure/Dashboard.jspa?selectPageId=17511), 
is one such example -- you can customize as you like.  So it is easy to 
track the lifecycle of JEPs that will affect the language and which will 
ultimately need IDE support.