We used to use the mango SPI processor, but this had two major issues:
* ecj wouldn't run annotation processors, requiring a separate proc:only compile run with javac
* mangoSPI couldn't do incremental compilation, so this required a full rebuild just to generate SPI files, every time.

Addressed by updating to IPP40 which does support explicit annotation processors even for ecj, and
adding our own SPI generating annotation processor to the build which can deal with incrementals.

There are some limits; removing a `@Provides` annotation on an existing type will need a full clean to pick that up, for example.
These limits seem quite exotic, though.

superbuilder generated the node `x.pluralName(plural == null ? Collections.emptyList() : plural)`.
java6 is not smart enough to infer the appropriate generics for the emptyList() call.
Fixed by always specifying the needed type explicitly: Collections.<String>emptyList();

 (chainable setters, static constructors, builder stuff)

Which 'flavour' is defined in lombok.config; applied to toString, equals, canEqual, and plural-form of `@Singular`.