public function getTypeMap()
{
if (null === $this->_typeMap) {
$map = [];
foreach ([$this->getQueryType(), $this->getMutationType(), Introspection::_schema()] as $type) {
$this->_extractTypes($type, $map);
}
$this->_typeMap = $map + Type::getInternalTypes();
}
return $this->_typeMap;
}