PcodeOp PIECE and inputs with mismatched sizes

[kotcrab]

I was trying to understand how two inputs with different sizes are joined: let's say one is 4 bytes and the other one is 8 bytes.
Looking at Java implementation that seems impossible, no matter which value is in1 or in2 they won't be joined correctly.
Then I found the C++ implementation and compared to Java it uses sizeout so joining those two inputs would work.

Seems suspicious that Java implementation is different, could this be a bug?