title: Fetch Post Request with Parameters is returning 400 status code?
body: <p>I have a Post Request using fetch in react native, but I get a status code 400 for this, what is wrong with the code?</p>
  <pre><code>function sendRequest2() {
      fetch(`https://sandbox-api.dexcom.com/v2/oauth2/token`, {
        method: &quot;POST&quot;,
        headers: {
          &quot;Content-Type&quot;: &quot;application/x-www-form-urlencoded&quot;,
        },
        body: JSON.stringify({
          code: &quot;value1&quot;,
          client_id: &quot;value2&quot;,
          client_secret: &quot;value3&quot;,
          redirect_uri: &quot;http://www.google.com&quot;,
          grant_type: &quot;authorization_code&quot;,
        }),
      })
        .then((response) =&gt; {
          response.json();
        })
        .then((data) =&gt; {
          console.log(data);
        })
        .catch((err) =&gt; console.log(&quot;The error is: &quot; + err));
    }
  </code></pre>