Mapping/Driver/DriverChain.php
public function loadMetadataForClass($className)
    {
        foreach ($this->drivers as $namespace => $driver) {
            if (strpos($className, $namespace) === 0) {
                return $driver->loadMetadataForClass($className);
            }
        }

        return null;
    }
public function loadMetadataForClass($className)
    {
        foreach ($this->drivers as $namespace => $driver) {
            if (strpos($className, $namespace) === 0) {
                return $driver->loadMetadataForClass($className);
            }
        }

        return null;
    }
Loads the metadata for the specified class

@param string $className The name of the class.

@return ClassMetadata|null The metadata for the specified class or null.