title: getOpenIdTokenForDeveloperIdentity: "These credentials are not valid for accessing this resource"
body: <p>I have set up a Cognito Identity Pool with a custom developer provider name "my.developer".  From my Node Lambda function I call the following code:</p>
  
  <pre><code>AWS.config.region = 'ap-northeast-1'; // Region
  AWS.config.credentials = new AWS.CognitoIdentityCredentials({
      IdentityPoolId: 'ap-northeast-1:*****'  // I am using a valid UUID here
  });
  var cognitoidentity = new AWS.CognitoIdentity();
  
  var params = {
      IdentityPoolId: 'ap-northeast-1:*****',
      Logins: { 'my.developer': 'test-user' }
  };
  cognitoidentity.getOpenIdTokenForDeveloperIdentity(params,
      function(err, data) {
          console.log('error:', err);
          console.log('data:', data);
      }
  );
  </code></pre>
  
  <p>...when I test the function I get an error:</p>
  
  <pre><code>{
    "errorMessage": "These credentials are not valid for accessing this resource",
    "errorType": "AccessDeniedException",
    "stackTrace": [
      "Request.extractError (/var/runtime/node_modules/aws-sdk/lib/protocol/json.js:43:27)",
  </code></pre>
  
  <p>I have Cognito_Unauth_Role and Cognito_Auth_Role which both resemble:</p>
  
  <pre><code>{
      "Version": "2012-10-17",
      "Statement": [
          {
              "Effect": "Allow",
              "Action": [
                  "mobileanalytics:PutEvents",
                  "cognito-sync:*",
                  "cognito-identity:*"
              ],
              "Resource": [
                  "*"
              ]
          }
      ]
  }
  </code></pre>
  
  <p>...what am I missing? </p>