title: React-Admin. how to filter the list on line entries for AutocompleteInput component
body: <p>version react-admin: 2.9.5</p>
  <p>My component:</p>
  <pre><code>&lt;ReferenceInput 
      label=&quot;Клиент&quot;
      source=&quot;customerId&quot; 
      reference=&quot;Customer&quot; 
      alwaysOn={true}
      filterToQuery={searchText =&gt; ({displayName: searchText})}
      &gt;
        &lt;AutocompleteInput optionText=&quot;displayName&quot;  /&gt;
  &lt;/ReferenceInput&gt;
  </code></pre>
  <p><strong>i'm expected that the request parameter filter will look like this</strong></p>
  <pre><code>contains(tolower(displayName),'fg')
  </code></pre>
  <p>but in reality it turns out to be</p>
  <pre><code>displayName eq 'fg'
  </code></pre>
  <p><strong>Ask: what I have to do to get the expected result?</strong></p>