"MaterialSetByMaterialType": {
  "type": "object",
  "additionalProperties": false,
  "title": "MaterialSetByMaterialType",
  "description": "The set of materials that match any of the material types listed.  An empty\nset is invalid since all targets require materials.",
  "required": ["MaterialTypes"],
  "properties": {
    "MaterialTypes": {
      "type": "array",
      "minItems": 1,
      "title": "Materialtypes",
      "items": {}
    }
  }
}

 "MaterialTypes": {
  "type": "array",
  "minItems": 1,
  "title": "Materialtypes",
  "items": {"type": "string"}
}

 "items": {"type": "string"}