Allow arbitrary task fields in project statistics filter

apiserver/bll/project/project_bll.py

@@ -809,12 +809,11 @@ class ProjectBLL:
         if not filter_:
             return conditions
 
-        for field in ("tags", "system_tags"):
-            field_filter = filter_.get(field)
-            if not field_filter:
-                continue
-            if not isinstance(field_filter, list) or not all(
-                isinstance(t, str) for t in field_filter
+        for field, field_filter in filter_.items():
+            if not (
+                field_filter
+                and isinstance(field_filter, list)
+                and all(isinstance(t, str) for t in field_filter)
             ):
                 raise errors.bad_request.ValidationError(
                     f"List of strings expected for the field: {field}"

apiserver/schema/services/projects.conf

@@ -582,15 +582,9 @@ get_all_ex {
     }
     "2.17": ${get_all_ex."2.16"} {
         request.properties.include_stats_filter {
-            description: The filter for selecting entities that participate in statistics calculation
+            description: The filter for selecting entities that participate in statistics calculation. For each task field that you want to filter on pass the list of allowed values. Prepend the value with '-' to exclude
             type: object
-            properties {
-                system_tags {
-                    description: The list of allowed system tags
-                    type: array
-                    items { type: string }
-                }
-            }
+            additionalProperties: true
         }
     }
 }