message: use std::sync::Once
diff: @@ -79,6 +79,7 @@ pub mod tests {
  static mut INSTITUTION_CONFIG: u32 = 0;
  static mut CONSUMER_CONFIG: u32 = 0;
  use indy::ErrorCode;
  + use std::sync::Once;
  static INIT_PLUGIN: std::sync::Once = Once::new();
  