[OTB] Fixes empty string parameters (#40957)

(cherry picked from commit 579d55f)

python/plugins/processing/algs/otb/OtbAlgorithm.py

@@ -201,8 +201,8 @@ def processAlgorithm(self, parameters, context, feedback):
         command = '"{}" {} {}'.format(app_launcher_path, self.name(), OtbUtils.appFolder())
         outputPixelType = None
         for k, v in parameters.items():
-            # if value is None for a parameter we don't have any businees with this key
-            if v is None:
+            # if value is None or en empty string for a parameter then we don't want to pass that value to OTB (see https://gitlab.orfeo-toolbox.org/orfeotoolbox/otb/-/issues/2130)
+            if v == '' or v is None:
                 continue
             # for 'outputpixeltype' parameter we find the pixeltype string from self.pixelTypes
             if k == 'outputpixeltype':

python/plugins/processing/tests/testdata/otb_algorithm_tests.yaml

@@ -64,3 +64,19 @@ tests:
       out:
         hash: 987b1488daaa16d09ad6f40039ee85101c557354a4d821d3f31ad235
         type: rasterhash
+
+  - algorithm: otb:Rasterization
+    name: Test empty string and zero integer parameters (otb:Rasterization)
+    params:
+      in:
+        name: polys.gml
+        type: file
+      epsg: EPSG:4326
+      spx: 1
+      spy: 1
+      mode.attribute.field: ""
+      outputpixeltype: 0
+    results:
+      out:
+        hash: c898326f9327dd0a111532fdacc5f43fc485ae3e10f1238b5da04dde
+        type: rasterhash