title: how to add placeholder text in the filter box in datatable column headers
body: <p>I have a prime faces datatable with few columns and have filteryBy attribute for all the columns. How do I add placeholder or watermark to provide hint for users. Any suggestions,will be appreciated thanks! </p>
  
  <pre><code>&lt;p:dataTable var="dt" widgetVar="widgetUserRecords"
                               value="#{userBean.result}"
                               id="userRecordTable" paginator="true"
                               paginatorAlwaysVisible="false" rows="10"
                               height="300" &gt;
  &lt;p:column sortBy="#{dt.course.name}" filterStyle="width:50px;"
                                filterBy="#{dt.course.name}" headerText="Course Name" style="text-align:bottom"&gt;
      &lt;h:outputText value="#{dt.course.name}"/&gt;
  &lt;/p:column&gt;
  .
  . 
  .
    (other columns)
  &lt;/p:dataTable&gt;
  </code></pre>