title: How to filter combined values using ag-grid in-built column filtering
body: <p>I have a column definition like this. I am combining more than one value to show as a title in title column. But the in built column filtering is returning empty rows whenever i type something in the column filter. What am i doing wrong here. Why column filtering is not working for combined values. How to achieve this.</p>
  
  <pre><code>title: {
                  minWidth: 90,
                  cellClassRules: {
                      'completedFieldClass': function(params) {
                          return params.value &amp;&amp; params.value.completed;
                      }
                  },
                  cellStyle: getCellStyle,
                  cellRenderer: function(params) {
                      var prqId = params.data.id;
                      var type = (!!params.data.type) ? params.data.type.value + ': ' : '';
                      var desc = (!!params.data.id) ? '- '+params.data.description : '';
  
                      if(!!params.data.access){
                          var concatTitle = '&lt;a&gt;';
                          concatTitle = concatTitle + '&lt;strong&gt;'+type+'&lt;/strong&gt;&lt;span&gt;'+params.value.value+'&lt;/span&gt;';
                          concatTitle = concatTitle + '&lt;span&gt;'+desc+'&lt;/span&gt;&lt;/a&gt;';
                          return concatTitle;
                      } else{
                          var concatTitle = '&lt;span class="notprint"&gt;';
                          concatTitle = concatTitle + '&lt;strong&gt;'+type+'&lt;/strong&gt;&lt;span&gt;'+params.value.value+'&lt;/span&gt;';
                          concatTitle = concatTitle + '&lt;span&gt;'+desc+'&lt;/span&gt;&lt;/span&gt;';
                          return concatTitle;
                          //return '&lt;span class="notprint"&gt;' + modValue + ''+ configDesc +'&lt;/span&gt;';
                      }
                  },
                  sortable: false
              },
  </code></pre>
  
  <p>Thanks in advance</p>