How can we insert multiple texts and paragraphs in google docs using google docs api with php?

I want to insert more the one texts in google docs with multiple paragraph contents and also want to style them. I also followed this link https://developers.google.com/docs/api/reference/rest/v1/documents/request but I am unable to achieve this.

$requests [] = new Google_Service_Docs_Request(
[
    'insertText' => [
        'text' => 'Sample1n',
        'location' => [
            'index' => 1
        ]
    ]
],
  [
    'insertText' => [
      'text' => 'sample2n',
      'location' => [
        'index' => 9
      ]
    ]
  ],
  [
    'updateParagraphStyle' => [
      'range' => [
        'startIndex' => 1,
        'endIndex' => 8
      ],
      'paragraphStyle' => [
        'namedStyleType' => 'HEADING_1'
      ],
      'fields' => 'namedStyleType'
    ]
  ],
  [
    'updateParagraphStyle' => [
      'range' => [
        'startIndex' => 9,
        'endIndex' => 17
      ],
      'paragraphStyle' => [
        'namedStyleType' => 'NORMAL_TEXT'
      ],
      'fields' => 'namedStyleType'
  ]
  ],
  [
    'updateTextStyle' => [
      'range' => [
        'startIndex' => 9,
        'endIndex' => 16
      ],
      'textStyle' => [
        'link' => [
          'url' => 'https://www.google.com'
        ]
      ],
      'fields' => 'link'
    ]
  ]
);
$batchUpdateRequest = new Google_Service_Docs_BatchUpdateDocumentRequest(array(
    'requests' => $requests
));

$response = $service->documents->batchUpdate($documentId, $batchUpdateRequest);

I am doing in this way and getting this error

PHP Fatal error:  Uncaught GoogleServiceException: {
  "error": {
    "code": 400,
    "message": "Invalid requests[0]: No request set.",
    "errors": [
      {
        "message": "Invalid requests[0]: No request set.",
        "domain": "global",
        "reason": "badRequest"
      }
    ],
    "status": "INVALID_ARGUMENT"
  }
}

Can anyone help me out with this. It would be a great help and i need it in PHP code.