src/Database/Schema/Index.php
public static function createName(array $columns, $type, $table = null)
    {
        $table = isset($table) ? trim($table).'_' : '';
        $type = trim($type);
        $name = strtolower($table.implode('_', $columns).'_'.$type);

        return str_replace(['-', '.'], '_', $name);
    }
public static function createName(array $columns, $type, $table = null)
    {
        $table = isset($table) ? trim($table).'_' : '';
        $type = trim($type);
        $name = strtolower($table.implode('_', $columns).'_'.$type);

        return str_replace(['-', '.'], '_', $name);
    }
Create a default index name.

@param array  $columns
@param string $type
@param string $table

@return string