private function findInstanceByCallbackType($instanceName) {
		// Note: we execute the code in another thread. Always.
		// This prevent crashing the main thread.
		try {
			$fullyQualifiedClassName = MoufReflectionProxy::getReturnTypeFromCode($this->declaredInstances[$instanceName]["code"], $this->getScope() == self::SCOPE_ADMIN);
			unset($this->declaredInstances[$instanceName]["error"]);
			unset($this->declaredInstances[$instanceName]["constructor"]);
			unset($this->declaredInstances[$instanceName]["fieldProperties"]);
			unset($this->declaredInstances[$instanceName]["setterProperties"]);
			unset($this->declaredInstances[$instanceName]["fieldBinds"]);
			unset($this->declaredInstances[$instanceName]["setterBinds"]);
			$this->declaredInstances[$instanceName]["class"] = $fullyQualifiedClassName;
		} catch (\Exception $e) {
			$this->declaredInstances[$instanceName]["error"] = $e->getMessage();
			unset($this->declaredInstances[$instanceName]["class"]);
			$fullyQualifiedClassName = null;
		}
		return $fullyQualifiedClassName;
	}