SNAPPY: Value for a parameter must be of type int

Microwave Toolbox Problem Reports
1
  • SNAP version: 12
  • SNAPPY version: 1.0.9
  • OS: Windows 11

This is my first time coding with esa-snappy.
And I am struggling from the very first step.
What I am trying to do is:

  1. Read a tiff file
  2. Apply Multilook

The multi-look coefficient is 3 in both range and azimuth directions.
But I got this error.

RuntimeError: org.esa.snap.core.gpf.OperatorException: Operator 'MultilookOp': Value for 'Number of Azimuth Looks' must be of type 'int'.

This is my code

from esa_snappy import ProductIO, GPF
source = ProductIO.readProduct('ICEYE_X8_GRD_SC_1953331_20230306T131247.tif')
parameters = esa_snappy.HashMap()
parameters.put('nRgLooks', 3)  # which is definitely of type 'int'
parameters.put('nAzLooks', 3)  # which is definitely of type 'int'
parameters.put('outputIntensity', True)
parameters.put('grSquarePixel', True)
source_mul = GPF.createProduct("Multilook", parameters, source)

Did I code something wrong?