title: Angular 7 + ag-Grid show incorrect warning in the console
body: <p>I am using Angular 7 and ag-Grid Community edition v19.x and use "sortable" attribute in my column def </p>
  
  <pre><code> this.columnDefs =  [
      {headerName: 'First Name ', field: 'firstName', sortable: true, filter: true },
      {headerName: 'Last Name', field: 'lastName', sortable: true, filter: true },
      {headerName: 'DOB', width: 150, field: 'dob', sortable: false, filter: false},        
      {headerName: 'Document', width: 400, field: 'documentName', sortable: true, filter: true},
      {headerName: 'Reference', field: 'reference'}
    ];
  </code></pre>
  
  <p>However, when I run the app , the console shows the following warning</p>
  
  <pre><code>ag-grid: invalid colDef property 'sortable' did you mean any of these: 
  </code></pre>