Hi, 

I have a problem with my code:

public class contractCallout {@future (callout=true)
    public static void PostCallout(String Id) {        
        
        Contract result =  [SELECT Id from contract where Id = '8004D000000HAdIQAW'];
        
        JSONGenerator gen = JSON.createGenerator(true);    
        gen.writeStartObject();      
        gen.writeStringField('Id', result.Id);
        /*gen.writeStringField('Origem_Contrato__c',result.Origem_Contrato__c);
        gen.writeStringField('Cotacao__r.Contact.FirstName',result.Cotacao__r.Contact.FirstName);
        gen.writeStringField('Cotacao__r.Contact.LastName',result.Cotacao__r.Contact.LastName);    */    
        gen.writeEndObject();    
        String jsonS = gen.getAsString();
        System.debug('jsonMaterials'+jsonS);
        
        // Sening the http body with JSON 
        
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals');
        request.setMethod('POST');
        request.setHeader('Content-Type', 'application/json;charset=UTF-8');
        request.setBody(jsonS);
        HttpResponse response = http.send(request);
        // Parse the JSON response
        if (response.getStatusCode() != 201) {
            System.debug('The status code returned was not expected: ' +
                response.getStatusCode() + ' ' + response.getStatus());
        } else {
            System.debug(response.getBody());
        }   
    } 
}


when I am going to take a test, it presents the following error: static can only be used on methods of a top level type 

Can someone help me?

Thanks