title: setCellType(CellType.STRING) is deprecated, Use explicit setCellFormula(String), setCellValue(...) or setBlank() to get the desired result
body: <p>poi version:4.1.2</p>
  <pre class="lang-java prettyprint-override"><code>@Deprecated
  @Removal(version = &quot;5.0&quot;)
  void setCellType(CellType cellType)
  </code></pre>
  <p>as noted in Cell class docs,it says <code>setCellType()</code> is deprecated, and suggests using <code>setCellFormula()</code> to realize the same function, but it doesn't give one example on how to realize it.</p>
  <p>The question is:
  How to use <code>setCellFormula()</code> to realize the same function as
  <code>setCellType(CellType.STRING)</code>?</p>