Magento2, custom widget save data wrong encoding

[mvistas]

I create a custom widget for magento2. I have one text parameter:

<parameter name="title" xsi:type="text"  visible="true" sort_order="1" >
            <label translate="true">Title</label>
        </parameter>

When I save data, if I use characters like à, or ã, or ü por example, the are saved with wrong encoding. For example ü became ü. This only happens on my widget. All the rest is saving with right encoding.

How can I set right encoding for a widget or a parameter?

thank you