framework/base/Module.php
public function init()
    {
        if ($this->controllerNamespace === null) {
            $class = get_class($this);
            if (($pos = strrpos($class, '\\')) !== false) {
                $this->controllerNamespace = substr($class, 0, $pos) . '\\controllers';
            }
        }
    }
public function init()
    {
        if ($this->controllerNamespace === null) {
            $class = get_class($this);
            if (($pos = strrpos($class, '\\')) !== false) {
                $this->controllerNamespace = substr($class, 0, $pos) . '\\controllers';
            }
        }
    }
Initializes the module.

This method is called after the module is created and initialized with property values
given in configuration. The default implementation will initialize [[controllerNamespace]]
if it is not set.

If you override this method, please make sure you call the parent implementation.