LessonsReportsGenerator::columns()

	protected function columns()
	{
		return [
			'user_id'         => $this->column('user_id'),
			'user'            => $this->column('user'),
			'course_id'       => $this->column('course_id'),
			'course'          => $this->column('course'),
			'lesson'          => [
				'label'     => __( 'Lesson', 'buddyboss' ),
				'sortable'  => true,
				'order_key' => 'post_title',
			],
			'start_date'      => $this->column('start_date'),
			'completion_date' => $this->column('completion_date'),
			'updated_date'    => $this->column('updated_date'),
			'time_spent'      => $this->column('time_spent'),
		];
	}