854      * @apiNote

   855      * An implementation may choose to not execute the stream pipeline (either

   856      * sequentially or in parallel) if it is capable of computing the count

   857      * directly from the stream source.  In such cases no source elements will

   858      * be traversed and no intermediate operations will be evaluated.

   859      * Behavioral parameters with side-effects, which are strongly discouraged

   860      * except for harmless cases such as debugging, may be affected.  For

   861      * example, consider the following stream:

   862      * <pre>{@code

   863      *     List<String> l = Arrays.asList("A", "B", "C", "D");

   864      *     long count = l.stream().peek(System.out::println).count();

   865      * }</pre>

   866      * The number of elements covered by the stream source, a {@code List}, is

   867      * known and the intermediate operation, {@code peek}, does not inject into

   868      * or remove elements from the stream (as may be the case for

   869      * {@code flatMap} or {@code filter} operations).  Thus the count is the

   870      * size of the {@code List} and there is no need to execute the pipeline

   871      * and, as a side-effect, print out the list elements.

   872      *