我使用以下命令test通过PUT请求创建索引：

PUT http://localhost:9250/test
{
    "settings": {
        "analysis": {
            "char_filter": {
                "&_to_and": {
                    "type": "mapping",
                    "mappings": ["& => and"]
                }
            },
            "filter": {
                "my_stopwords": {
                    "type":       "stop",
                    "stopwords": ["the", "a"]
                }
            },
            "analyzer": {
                "my_analyzer": {
                    "type":         "custom",
                    "char_filter":  ["html_strip", "&_to_and"],
                    "tokenizer":    "standard",
                    "filter":       ["lowercase", "my_stopwords"]
                },
                "folding": {
                    "token_filters": ["lowercase", "asciifolding"],
                    "tokenizer": "standard",
                    "type": "custom"
                }
            }
        }
    },
    "mappings": {
        "tweet": {
            "dynamic": "strict",
            "properties": {
                "author": {
                    "type": "string",
                    "index": "my_analyzer",
                    "store": true
                },
                "text": {
                    "type": "string",
                    "index": "folding",
                    "store": true
                },
                "timestamp": {
                    "type": "date",
                    "format": "yyyy-MM-dd'T'HH:mm:ssZ",
                    "store": true
                }
            }
        }
    }
}

但这返回以下错误：

{
  "error": {
    "root_cause": [
      {
        "type": "mapper_parsing_exception",
        "reason": "wrong value for index [my_analyzer] for field [author]"
      }
    ],
    "type": "mapper_parsing_exception",
    "reason": "Failed to parse mapping [tweet]: wrong value for index [my_analyzer] for field [author]",
    "caused_by": {
      "type": "mapper_parsing_exception",
      "reason": "wrong value for index [my_analyzer] for field [author]"
    }
  },
  "status": 400
}

我发送的json似乎有效。此错误的原因是什么？

我正在使用ES 2.2.0。