Fix join with point layer in object level

  "integration_scheme": [
      {
          "spatial_relation": "NEAREST",
          "out": {
              "name": "stations",
              "level": "OBJECTS"
          },
          "in": {
              "name": "airtemp",
              "level": "COORDINATES3D"
          },
          "operation": "DISCARD",
          "abstract": true
      }
  ]