title: sap.m.Select: start with a blank selection input element
body: <p>When using a data aggregation on <code>sap.m.Select</code>, the first entry is always selected. Here's a link to the <a href="https://sapui5.netweaver.ondemand.com/sdk/explored.html#/sample/sap.m.sample.Select/preview" rel="noreferrer">SDK's preview</a>.</p>
  
  <p>Example code from my app</p>
  
  <pre><code>new sap.m.Select("id-names", {
      width: '100%',
  }).bindAggregation("items", "data&gt;/trip/names", new sap.ui.core.Item({
      text: "{data&gt;Name}"
  }));
  </code></pre>
  
  <p>There is a parameter called <code>selectedKey</code> on the constructor to change this to another index. What I want is the select to be <strong>blank</strong>, because I want to force my users to make a choice, not blandly accept the first entry in the list. </p>
  
  <p>I could force an blank entry in my aggregation <code>data&gt;/trip/names</code> but that would pollute my list. </p>
  
  <p>Is there a better way to achieve this?</p>