MDL-58415 mod_lesson: Return always allowofflineattempts

We need this field always to be able to display if the lesson is
available or not for download

mod/lesson/classes/external.php

@@ -65,7 +65,7 @@ class mod_lesson_external extends external_api {
                 'maxanswers', 'maxattempts', 'review', 'nextpagedefault', 'feedback', 'minquestions',
                 'maxpages', 'timelimit', 'retake', 'mediafile', 'mediaheight', 'mediawidth',
                 'mediaclose', 'slideshow', 'width', 'height', 'bgcolor', 'displayleft', 'displayleftif',
-                'progressbar', 'allowofflineattempts');
+                'progressbar');
 
             foreach ($fields as $field) {
                 unset($lessonrecord->{$field});

mod/lesson/classes/external/lesson_summary_exporter.php

@@ -249,7 +249,6 @@ class lesson_summary_exporter extends exporter {
             'allowofflineattempts' => array(
                 'type' => PARAM_BOOL,
                 'description' => 'Whether to allow the lesson to be attempted offline in the mobile app',
-                'optional' => true,
             ),
         );
     }

mod/lesson/tests/external_test.php

@@ -1304,7 +1304,7 @@ class mod_lesson_external_testcase extends externallib_advanced_testcase {
         // Lesson not using password.
         $result = mod_lesson_external::get_lesson($this->lesson->id);
         $result = external_api::clean_returnvalue(mod_lesson_external::get_lesson_returns(), $result);
-        $this->assertCount(5, $result['lesson']);   // Expect just this few fields.
+        $this->assertCount(6, $result['lesson']);   // Expect just this few fields.
         $this->assertFalse(isset($result['intro']));
     }