Issue #3271394 by RenatoG: Settings for quantity of classes appearing wrongly...

      '#title' => $this->t("Quantity of classes per block"),

      '#type' => 'number',

      '#default_value' => $qty_classes_per_block,

      // Show the qty_classes_per_block only when the field type is multiple

      // because is the only type that is used.

      '#states' => [

        'visible' => [

          ':input[name="field_type"]' => ['value' => 'multiple_textfields'],

        ],

      ],

    ];

    $maxlength_block_class_field = 255;