Python snappy Back-Geocoding wong result

hello ,

i want to follow this STEP Forum Back-GeocodingOp with multiple slaves in snappy to use GeocodingOp with python.

mst = ProductIO.readProduct('path/to/mst.dim')
slv = ProductIO.readProduct('path/to/slv.dim') 

prodset = []
prodset.append(slv)
prodset.append(mst)

parameters = HashMap()
parameters.put('demName', "SRTM 3Sec")
parameters.put('demResamplingMethod', 'BICUBIC_INTERPOLATION')
parameters.put('resamplingType', 'BISINC_5_POINT_INTERPOLATION')
parameters.put('maskOutAreaWithoutElevation', True)
parameters.put('outputDerampDemodPhase', False)

prodset_bgc = GPF.createProduct('Back-Geocoding', parameters, prodset)
ProductIO.writeProduct(prodset_bgc, 'bg.dim', 'BEAM-DIMAP')

and with :

prodset_bgc = GPF.createProduct('Back-Geocoding', parameters, [slv,mst])

The result if i use this python code is wrong because in bg.dim has only master layers and not slave layers.

If i use SNAP GUI then create a file with master and slave layers ,

What i have wrong ?

thank you