src/Type/Definition/ObjectType.php
public function hasField($name)
    {
        if ($this->fields === null) {
            $this->getFields();
        }

        return isset($this->fields[$name]);
    }
public function hasField($name)
    {
        if ($this->fields === null) {
            $this->getFields();
        }

        return isset($this->fields[$name]);
    }
@param string $name

@return bool