title: setLayoutParams on ConstraintLayout does not change size
body: <p><strong>Story</strong></p>
  
  <p>I have 2 textviews, one on top of another:</p>
  
  <pre><code>XXXXXXXXXXXX[TextView1]
  XXXXXXXXXXXX[TextView2]
  </code></pre>
  
  <ul>
  <li>Both TextViews aligns to the right. (Hence the XXX above)</li>
  <li>TextView1 has a background color.</li>
  <li>TextView2 is always longer than TextView1</li>
  <li>TextView1's left must be aligned with TextView2</li>
  </ul>
  
  <p>I have the above 4 requirements. Now everything works well by using ConstraintLayout, where TextView1's left is constrained to TextView2's left, and TextView2's width is <code>wrap_content</code>.</p>
  
  <p>But now it comes the 5th requirement:</p>
  
  <ul>
  <li>TextView2 can disappear, leaving TextView1 behind.</li>
  </ul>
  
  <p><code>setVisibility(GONE)</code> does not work, because TextView2 must be <code>wrap_content</code>. it will become 0 in width and therefore TextView1 as well (since its left is constrained to TextView2's left)</p>
  
  <p>Then I tried to set TextView2's height to be 0, using the below code:</p>
  
  <pre><code>    ConstraintLayout.LayoutParams lp = (ConstraintLayout.LayoutParams)textView2.getLayoutParams();
      lp.width = widthInPixelOrConstant;
      textView2.setLayoutParams(lp);
  </code></pre>
  
  <p>Oops, nothing happens. TextView2 remains there, as if nothing happened.
  I Googled for half an hour, and finally decided to wrap <code>TextView2</code> in a <code>LinearLayout</code>.</p>
  
  <p>And then using the below code to set height of TextView2 to be 0:</p>
  
  <pre><code>    LinearLayout.LayoutParams lp = (LinearLayout.LayoutParams )view.getLayoutParams();
      lp.width = widthInPixelOrConstant;
      view.setLayoutParams(lp);
  </code></pre>
  
  <p>......It works!!!</p>
  
  <p><strong>The Question</strong></p>
  
  <p>So, apparently, we cannot use what we used before - <code>setLayoutParams</code> to try to alter the height or width of a ConstraintLayout's child at runtime.<br>
  But then, wrapping that TextView2 in a LinearLayout is really stupid.<br>
  Does anyone knows how to change a ConstraintLayout's child width or height at runtime?</p>