public function registerFormatter(string $name, callable $formatter) : self
    {
        $this->credentialFormatters[$name] = $formatter;
        return $this;
    }
public function registerFormatter(string $name, callable $formatter) : self
    {
        $this->credentialFormatters[$name] = $formatter;
        return $this;
    }
public function registerFormatter ( string $ name , callable $ formatter ) : self { $ this -> credentialFormatters [ $ name ] = $ formatter ; return $ this ; }
Adds a credential formatter to the configuration.

A credential formatter is responsible for formatting the credentials for a relationship
in a way expected by a particular client library.  For instance, it can take the credentials
from Platform.sh for a PostgreSQL database and format them into a URL string expected by
PDO.  Use the formattedCredentials() method to get the formatted version of a particular
relationship.

@param string name
The name of the formatter.  This may be any arbitrary alphanumeric string.
@param {registerFormatterCallback} formatter
A callback function that will format relationship credentials for a specific client library.
@return Config
The called object, for chaining.
Adds a credential formatter to the configuration .