@Override
    public void error(String message, Throwable error) {
        loggerA.error(message, error);
        loggerB.error(message, error);
    }
Constructor.
<p>
Loggers are logged to in the order provided to this constructor (i.e. loggerA then loggerB).

@param loggerA first logger
@param loggerB second logger
common/logging/core/src/main/java/io/apiman/common/logging/impl/DoubleLogger.java