aStringBuffer + anObject gives runtime error

From <oni> on #groovy
>
>
> println ( buffer + key + value);
>
> results in an error of No signature of method
> java.lang.StringBuffer.plus() is applicable
>
> buffer is of type StringBuffer
> if i use buffer.toString()
> it works fine

I assume the java compiler turns all the (buffer + key + value) into (buffer.append(key).append(value))
but the groovy plus() isn't quite as smart...?
either a compiler change, or a new DGM plus method perhaps..?

Thanks for this oni.