SameDiff Pooling3D op serialized/deserializes as wrong type

[rnett]

The Pooling3D op is used by SDCNN.avgPooling and maxPooling, with the mode set as a config option. However, when these are serialized and deserialized, they turn into AvgPooling3D and MaxPooling3D ops respectively.

To reproduce:

@Test
public void pooling3DSerialization(){
    SameDiff sd = SameDiff.create();

    SDVariable x = sd.placeHolder("x", DataType.FLOAT, 1, 28, 28);
    SDVariable o = sd.cnn.maxPooling3d("pool", x, Pooling3DConfig.builder().build());

    ByteBuffer bbSerialized = sd.asFlatBuffers();

    SameDiff deserialized;
    try{
        deserialized = SameDiff.fromFlatBuffers(bbSerialized);
    } catch (IOException e){
        throw new RuntimeException("IOException deserializing from FlatBuffers", e);
    }
    assertEquals(
            sd.getVariableOutputFunction("pool").getClass(),
            deserialized.getVariableOutputFunction("pool").getClass());
}

@Test
public void pooling3DSerialization2(){
    SameDiff sd = SameDiff.create();

    SDVariable x = sd.placeHolder("x", DataType.FLOAT, 1, 28, 28);
    SDVariable o = sd.cnn.avgPooling3d("pool", x, Pooling3DConfig.builder().build());

    ByteBuffer bbSerialized = sd.asFlatBuffers();

    SameDiff deserialized;
    try{
        deserialized = SameDiff.fromFlatBuffers(bbSerialized);
    } catch (IOException e){
        throw new RuntimeException("IOException deserializing from FlatBuffers", e);
    }
    assertEquals(
            sd.getVariableOutputFunction("pool").getClass(),
            deserialized.getVariableOutputFunction("pool").getClass());
}