Wordpress HTTP API code 400

我正在研究POS系统的API集成，该系统需要安全令牌。在API文档&旋度响应是可以的。

旋度

curl -X POST --header "Content-Type: application/json" --header "Accept: */*" -d "{
   '"deviceId'": '"api'",
   '"password'": '"password'",
   '"username'": '"ursername@pos.com'"
}" "http://staging-exact-integration.posios.com/PosServer/rest/token"

请求URL

http://staging-exact-integration.posios.com/PosServer/rest/token

然而，当我试图在Wordpress HTTP API中编写它时，我得到了400个坏请求。说

[body] => {"description":"Could not read JSON: No content to map due to end-of-input'n at [Source: org.eclipse.jetty.server.HttpInput@62421932; line: 1, column: 1]; nested exception is com.fasterxml.jackson.databind.JsonMappingException: No content to map due to end-of-input'n at [Source: org.eclipse.jetty.server.HttpInput@62421932; line: 1, column: 1]"}

在Wordpress

$url = "http://staging-exact-integration.posios.com/PosServer/rest/token";
$response = wp_remote_post( $url, array(
    "headers" => array(
        //"Authorization" => "Basic",
        "Content-Type" => "application/json"
    ),
    //"body" => "grant_type=client_credentials",
    //"httpversion" => "1.1",
    "deviceId" => "api",
    "password" => "password",
    "username" => "username@pos.com"
    )
);
if ( is_wp_error( $response ) ) {
   $error_message = $response->get_error_message();
   echo "Something went wrong: $error_message";
} else {
   echo 'Response:<pre>';
   print_r( $response );
   echo '</pre>';
}

在Wordpress HTTP API中需要什么?

{
  "title": {
  "raw": "Hello Checking"
}