How to get viewhelper f:widget.autocomplete working in TYPO3 8.7 - autocomplete

Question

I want to use the viewhelper f:widget.autocomplete to implement an autocomplete feature for a search in a little extension in TYPO3 8.7.
The Documentation for TYPO3 8.7. says nothing about it: https://docs.typo3.org/m/typo3/guide-extbasefluid/8.7/en-us/Fluid/ViewHelper/Widget/Autocomplete.html
I tried it as discribed in the Documentation for TYPO3 9.5. https://docs.typo3.org/other/typo3/view-helper-reference/9.5/en-us/typo3/fluid/latest/Widget/Autocomplete.html
I have included the JS- and CSS-Assets and use the viewhelper in the filter-form of my extension:
<input type="text" id="search" name="pluginname[search]" />
<f:widget.autocomplete for="search" objects="{myobject}" searchProperty="name" />
This integrates a JS-Snippet from sysext/fluid and makes an ajax call, if I put something in the text field.:
http://host/index.php?id=1&type=7076&fluid-widget-id=305d544b2a96a8e5a73db7e93c083586&action=autocomplete&term=myterm
But the response to this call contents the hole page and not only the result of a datatabase query according to my searchterm.
Now my question:
What have I to do, to get the autocomplete feature working?
Do I need an extra autocomplete action in my controller?
Or ist there an extra setup for the pageType needed?
Currently the pageType 7076 is configured by the Fluid-Sysextension:
fluidAjaxWidgetResponse = PAGE
fluidAjaxWidgetResponse {
# todo: make page type configurable
typeNum = 7076
headerData >
config {
no_cache = 1
disableAllHeaderCode = 1
additionalHeaders.10.header = Content-Type: text/plain
additionalHeaders.10.replace = 1
debug = 0
}
10 = USER_INT
10 {
userFunc = TYPO3\CMS\Fluid\Core\Widget\Bootstrap->run
}
}
config.tx_extbase {
mvc {
requestHandlers {
TYPO3\CMS\Fluid\Core\Widget\WidgetRequestHandler = TYPO3\CMS\Fluid\Core\Widget\WidgetRequestHandler
}
}
}