code: public OvhInstanceDetail project_serviceName_instance_instanceId_resize_POST(String serviceName, String instanceId, String flavorId) throws IOException {
  		String qPath = "/cloud/project/{serviceName}/instance/{instanceId}/resize";
  		StringBuilder sb = path(qPath, serviceName, instanceId);
  		HashMap<String, Object>o = new HashMap<String, Object>();
  		addBody(o, "flavorId", flavorId);
  		String resp = exec(qPath, "POST", sb.toString(), o);
  		return convertTo(resp, OvhInstanceDetail.class);
  	}
docs: Migrate your instance to another flavor
  
  REST: POST /cloud/project/{serviceName}/instance/{instanceId}/resize
  @param flavorId [required] Flavor id
  @param instanceId [required] Instance id
  @param serviceName [required] Service name