code: private <R> R requiredInternal(final SQLSupplier<R> supplier) {
  		if (currentTxContext().isPresent()) {
  			return supplier.get();
  		} else {
  			return runInNewTx(supplier);
  		}
  	}
docs: requiredメソッドの内部実装
  
  @param supplier SQLサプライヤ
  @return 実行結果
  @throws SQLException SQL例外