Sets the enumerator to its initial position, which is before the first
element in the collection.
An enumerator remains valid as long as the collection remains
unchanged. If changes are made to the collection, such as adding,
modifying, or deleting elements, the enumerator is irrecoverably
invalidated. The next call to
#moveNext or
reset may,
at the discretion of the implementation, throw a
java.util.ConcurrentModificationException.
This method is optional; it may throw
UnsupportedOperationException.
Notes to Implementers
All calls to Reset must result in the same state for the enumerator.
The preferred implementation is to move the enumerator to the beginning
of the collection, before the first element. This invalidates the
enumerator if the collection has been modified since the enumerator was
created, which is consistent with
#moveNext() and
#current().