Investigate "ForIteration" behavior

[gitgabrio]

The current implementation of ForIteration has the following details

1. it use an underlying Iterator for its operations
2. the Iterator is not instantiated immediately, but delegated to a Supplier
3. the iterator is actually instantiated only when  hasNextValue is invoked
4. if the underling iterator.hasNext() return false, then the iterator is set to null
5. the getNextValue() does not instantiate the iterator by itself, so if the hasNextValue() has not been called before, it returns null
6. the semantic is therefore different then the usual one provided by the iterators themselves

A quick experiment, removing the supplier and using the class to simple "facade" of the underlying iterator, lead to test failuers; e.g.

"for x in [ 10, 20, 30 ], y in [ 1, 2, 3 ] return x * y"
->

Expecting actual:
  [10, 20, 30]
to contain exactly (and in same order):
  [10, 20, 30, 20, 40, 60, 30, 60, 90]
but could not find the following elements:
  [20, 40, 60, 30, 60, 90]

That could be the sympton that there is some existing logic, outside this class itself, that is based on the null object returned.