static function getInstance( eZContentObjectAttribute $objectAttribute )
    {
        //Patch for performance issues by Amaury SECHET
        
        //Original test from eZ publish
        //if ( array_key_exists( $objectAttribute->attribute( 'id' ), self::$singletons ) )
        if ( isset( self::$singletons[$objectAttribute->attribute( 'id' )] ) )
        {
            return self::$singletons[$objectAttribute->attribute( 'id' )];
        }
        else
        {
            $datatypeString = $objectAttribute->attribute( 'data_type_string' );

            // Check if using custom handler.
            $customMapList = self::$FindINI->variable( 'SolrFieldMapSettings', 'CustomMap' );
            //Original test from eZ publish
            //if ( array_key_exists( $datatypeString, $customMapList ) )
            if ( isset( $customMapList[$datatypeString] ) )
            {
                $fieldBaseClass = $customMapList[$datatypeString];
                if ( class_exists( $fieldBaseClass ) )
                {
                    self::$singletons[$objectAttribute->attribute( 'id' )] = new $customMapList[$datatypeString]( $objectAttribute );
                    return self::$singletons[$objectAttribute->attribute( 'id' )];
                }
                else
                {
                    eZDebug::writeError( "Unknown document field base class '$fieldBaseClass' for datatype '$datatypeString', check your ezfind.ini configuration", __METHOD__ );
                }
            }

            // Return standard handler.
            self::$singletons[$objectAttribute->attribute( 'id' )] = new ezfSolrDocumentFieldBase( $objectAttribute );
            return self::$singletons[$objectAttribute->attribute( 'id' )];
        }
    }