Convert code blocks in comments using array() syntax to @code/@endcode

Closes #3454142

core/lib/Drupal/Component/Gettext/PoHeader.php

@@ -440,20 +440,24 @@ private function tokenizeFormula($formula) {
    * An example of plural formula parting and evaluation:
    *   Plural formula: 'n!=1'
    * This formula is parsed by parseArithmetic() to a stack (array) of elements:
-   *   array(
+   * @code
+   *   [
    *     0 => '$n',
    *     1 => '1',
    *     2 => '!=',
-   *   );
+   *   ];
+   * @endcode
    * The evaluatePlural() method evaluates the $element_stack using the plural
    * value $n. Before the actual evaluation, the '$n' in the array is replaced
    * by the value of $n.
    *   For example: $n = 2 results in:
-   *   array(
+   * @code
+   *   [
    *     0 => '2',
    *     1 => '1',
    *     2 => '!=',
-   *   );
+   *   ]
+   * @endcode
    * The stack is processed until only one element is (the result) is left. In
    * every iteration the top elements of the stack, up until the first operator,
    * are evaluated. After evaluation the arguments and the operator itself are
@@ -462,9 +466,11 @@ private function tokenizeFormula($formula) {
    *   Because the operator is '!=' the example stack is evaluated as:
    *   $f = (int) 2 != 1;
    *   The resulting stack is:
-   *   array(
+   * @code
+   *   [
    *     0 => 1,
-   *   );
+   *   ]
+   * @endcode
    * With only one element left in the stack (the final result) the loop is
    * terminated and the result is returned.
    *