title: Unique "key" prop warning in render method - ReactJS
body: <p>My app have a warning say that: <code>Each child in an array or iterator should have a unique "key" prop. Check the render method of 'SortableTable'</code> Hear is my SortableTable file:</p>
  
  <pre><code>import React from 'react';
  import {Link} from 'react-router';
  import {v4 as uuid} from 'node-uuid';
  
  export default class SortableTable extends React.Component {
      render() {
  
          return (
              &lt;table style={{width: '100%'}} className={this.props.className} id={this.props.id}&gt;
                  &lt;thead&gt;
                      &lt;tr&gt;
                          {this.props.headers.map(this.generateHeaders)}
                      &lt;/tr&gt;
                  &lt;/thead&gt;
                  &lt;tbody&gt;
                      {this.props.children}
                  &lt;/tbody&gt;
              &lt;/table&gt;
          );
      }
  
      generateHeaders = (value) =&gt; {
          if (Object.keys(value).length === 0) return
          let sort, colspan
          if(value.sort) {
  
              let {query} = this.props;
              let nQuery, title, icon, colspan = 1;
              if(query.sort === value.sort &amp;&amp; query.sortDirection === 'desc') {
                  nQuery = Object.assign({}, query, {sort: value.sort, sortDirection: 'asc', page: 1})
                  title = 'asc';
                  icon = String.fromCharCode(0xe630)
              } else {
                  nQuery = Object.assign({}, query, {sort: value.sort, sortDirection: 'desc', page: 1})
                  title = 'desc';
                  icon = String.fromCharCode(0xe62d)
              }
              sort = &lt;Link to={this.props.link} query={nQuery} className="icon order active" title={title} data-icon={icon} /&gt;
  
          }
          let className = value.className ? value.className : ''
          if(value.colspan) {
              colspan = value.colspan
          }
          return &lt;th className={className} colSpan={colspan}&gt;&lt;span&gt;{value.name}&lt;/span&gt;{sort}&lt;/th&gt;
      }
  </code></pre>
  
  <p>Can someone show me how to set key prop to resolve this warning?</p>