// Returns true if any key from base is overridden in object
local isAnyKeyOverridden = function (base, object)
  local keys = std.objectFields(base);
  std.foldl(function(acc, field) acc || base[field] != object[field], keys, false);

local base = {
  paramA: null,
  paramB: null,
};

base + {
  assert !isAnyKeyOverridden(base, $),
}

local base = import "test.jsonnet";
local Parameterized = base + { paramA:: 3 };
Parameterized

RUNTIME ERROR: Object assertion failed.
        ../universe/test.jsonnet:12:10-38       thunk <object_assert>
        During manifestation

{
   "paramB": null
}