The Common API package is a collection of really low-level types needed at the core of the Zest™ Runtime. It is also a collection of types that are not particularly cohesive, and effectively this package contains the loose ends that does not belong elsewhere.
In this package, you can safely ignore the following classes;
UNLESS you are into deep integration into the Zest™ Runtime.
This tandem of interface + annotation are primarily used for Generic Fragments, to indicate which methods on the interface the fragment should be applied to.
In Zest™, method arguments, property values and injected fields are not allowed to be null by default. To allow any of these to be null, i.e. undeclared, it is required that the argument, field or method is marked with the @Optional annotation.
Since null is not allowed without the @Optional annotation, it can sometimes by tedious to initialize all the property values. And the @UseDefaults annotation allows us to declare that Zest™ should set the Property to a default value. These are either the pre-defined ones, or can be set per property declaration during the assembly.
Visibility is another innovative concept in Zest™, which leverage the structure system (Application, Layer, Module) to limit the 'reach' when requesting composites and objects. The Visibility is declared per Composite/Object, preferably in the most restrictive mode possible, and the visibility resolver will ensure a predictable resolution algorithm;
Visibility.module
. If one and only one composite type fulfilling the request is available
return that to the caller. If two or more are found, throw an AmbiguousTypeException. If no composite found
continue to the next step.
Visibility.application
. If one and only one composite type fulfilling the request is available
return that to the caller. If two or more are found, throw an AmbiguousTypeException. If no composite found
continue to the next step.