[GitHub] brooklyn-server pull request #408: Use actual config key if available in DSL

[aledsage <gi...@git.apache.org>]

Github user aledsage commented on a diff in the pull request:

    https://github.com/apache/brooklyn-server/pull/408#discussion_r86738337
  
    --- Diff: camp/camp-brooklyn/src/main/java/org/apache/brooklyn/camp/brooklyn/spi/dsl/methods/DslComponent.java ---
    @@ -144,7 +147,7 @@ public Entity call() throws Exception {
             
             protected Maybe<Entity> callImpl(boolean immediate) throws Exception {
                 Maybe<Entity> entityMaybe = getEntity(immediate);
    -            if (immediate && entityMaybe.isAbsent()) {
    +            if (immediate && entityMaybe.isAbsentOrNull()) {
    --- End diff --
    
    Is this to avoid the `NullPointerException` you saw before https://github.com/apache/brooklyn-server/pull/404 was merged? I wondered about this.
    
    The problem with returning `Maybe.of(null)` if the entity can't be resolved is that it's different semantics from `deferredSupplier.get()`. For the latter, it would throw `NoSuchElementException` with a nice message explaining it. Now this will just return a null.
    
    The intent is that `getImmediately()` will either return `absent()` if it can't be resolved immediately, or will return immediately exactly the same value as `get()` would.


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