code: public static <T> Collection<T> findAll(Collection<T> self) {
          return findAll(self, Closure.IDENTITY);
      }
docs: Finds the items matching the IDENTITY Closure (i.e.&#160;matching Groovy truth).
  <p>
  Example:
  <pre class="groovyTestCase">
  def items = [1, 2, 0, false, true, '', 'foo', [], [4, 5], null]
  assert items.findAll() == [1, 2, true, 'foo', [4, 5]]
  </pre>
  
  @param self    a Collection
  @return a Collection of the values found
  @since 1.8.1
  @see Closure#IDENTITY