anchor.diff:  [tck-testable]
   --
   `BeanNode`, `PropertyNode` and `ContainerElementNode` host `getContainerClass()` and `getTypeArgumentIndex()`.
  -If the constrained element is contained in a generic container such as `Optional`, `List` or `Map`,
  -the former returns the class of the container and the latter returns the index of the affected type argument.
  +If the node represents an element that is contained in a generic container such as `Optional`, `List` or `Map`,
  +the former returns the declared type of the container and the latter returns the index of the affected type argument.
   --
   
   .Narrow a node to its specific type
  
positive.code: ** [tck-testable]#if the association is a [classname]`List` or an array, the following [classname]`Node` object added contains the index value in [methodname]`getIndex()`.#
  ** [tck-testable]#if the association is a [classname]`Map`, the following [classname]`Node` object added (representing a given map entry) contains the key value in [methodname]`getKey()`#
  ** [tck-testable]#for all [classname]`Iterable` or [classname]`Map`, the following [classname]`Node` object added is marked as `inIterable` ([methodname]`isInIterable()`)#
  ** [tck-testable]#if the traversed object is of a container type (e.g. a `List` or `Map`), the following `Node` object added returns the type of the traversed container via `getContainerClass()` and the index of the type argument to which the constraint applies via `getTypeArgumentIndex()`#
  
  [tck-testable]
  --
  
negative.code: 
  ** a [classname]`ContainerElementNode` object is added to [classname]`Path` whose `name` is the node name produced by the corresponding value extractor (see <<valueextractordefinition>>).
  The [classname]`ElementKind` of the node is [varname]`ElementKind.CONTAINER_ELEMENT`.
  `getContainerClass()` returns the declared type of the container hosting the constraint.
  `getTypeArgumentIndex()` returns the index of the type argument hosting the constraint.
  ** the property path is considered complete
  --
  
  