title: Find all docs where field of type double is equal to empty string
body: <h1>Problem</h1>
  <p>I'm trying to find all documents that have a particular field set to the empty string.</p>
  <p>But this field is of type <code>double</code> and that complicates things...</p>
  <p>I can't use <code>term</code> or <code>match</code> query because the field is of type <code>double</code>. I get a <code>number_format_exception</code>.</p>
  <p>I'm currently using the following:</p>
  <pre class="lang-json prettyprint-override"><code>{
      &quot;query&quot;: {
          &quot;bool&quot;: {
              &quot;must_not&quot;: [
                  {
                     &quot;exists&quot;: {
                          &quot;field&quot;: &quot;my_double_field&quot;
                      }
                  }
              ]
              
          }
      },
      &quot;size&quot;: 100
  }
  </code></pre>
  <p>This returns all docs where <code>my_double_field</code> is equal to <code>&quot;&quot;</code> AND the docs where <code>my_double_field</code> does not exist at all.</p>
  <h1>Question</h1>
  <p>Is there a query to return docs if and only if this field is set to <code>&quot;&quot;</code>?</p>