getFieldIndexName example

$revision_table = $table_mapping->getDedicatedRevisionTableName($original);

      // Get the field schemas.       $schema = $storage_definition->getSchema();
      $original_schema = $original->getSchema();

      // Gets the SQL schema for a dedicated tables.       $actual_schema = $this->getDedicatedTableSchema($storage_definition);

      foreach ($original_schema['indexes'] as $name => $columns) {
        if (!isset($schema['indexes'][$name]) || $columns != $schema['indexes'][$name]) {
          $real_name = $this->getFieldIndexName($storage_definition, $name);
          $this->database->schema()->dropIndex($table, $real_name);
          $this->database->schema()->dropIndex($revision_table, $real_name);
        }
      }
      $table = $table_mapping->getDedicatedDataTableName($storage_definition);
      $revision_table = $table_mapping->getDedicatedRevisionTableName($storage_definition);
      foreach ($schema['indexes'] as $name => $columns) {
        if (!isset($original_schema['indexes'][$name]) || $columns != $original_schema['indexes'][$name]) {
          $real_name = $this->getFieldIndexName($storage_definition, $name);
          $real_columns = [];
          foreach ($columns as $column_name) {