Problem with sorting polish words(ES 2.4.6)

Elastic Stack Elasticsearch
1

Hello.
Wrong sorting result for product name with polish characters.

ElasticSearch Version: 2.4.6, Build: 5376dca/2017-07-18T12:17:44Z, JVM: 1.7.0_151
"version" : {
"number" : "2.4.6",
"build_hash" : "5376dca9f70f3abef96a77f4bb22720ace8240fd",
"build_timestamp" : "2017-07-18T12:17:44Z",
"build_snapshot" : false,
"lucene_version" : "5.5.4"
},

Plugins: Installed plugins in /usr/share/elasticsearch/plugins:
- analysis-stempel
- analysis-phonetic
- analysis-icu

Steps to reproduce
I added 4 rows with names:
Łatwa naz
Latwa naz
Łatwa naa
Latwa naa

I search by "latwa" and sorting by "name" DESC

Expected result
Łatwa naz
Łatwa naa
Latwa naz
Latwa naa

"Ł" should be before "L"

Actual result
Łatwa naz
Latwa naz
Łatwa naa
Latwa naa

Configuration:
"pl_ascii_folding": {
"type": "asciifolding",
"preserve_original": "1"
},

"sortable": {
"type": "custom",
"filter": [
"pl_ascii_folding",
"lowercase"
],
"tokenizer": "keyword"
}
Query:
?q=name:latwa&sort=name.sortable:DESC'

Problem from Problem with sort with polish(POLAND) words! is not the same.

For ElasticSearch version 6.1 is ok.

2

This behaviour is surprising to me, can you share a full recreation including mappings?

3 
{
  "magento2_default_catalog_product_20180124_102302": {
    "mappings": {
      "product": {
        "_all": {
          "enabled": false
        },
        "properties": {
          "name": {
            "type": "string",
            "norms": {
              "enabled": false
            },
            "fielddata": {
              "format": "disabled"
            },
            "fields": {
              "shingle": {
                "type": "string",
                "norms": {
                  "enabled": false
                },
                "index_options": "docs",
                "fielddata": {
                  "format": "disabled"
                },
                "analyzer": "shingle"
              },
              "sortable": {
                "type": "string",
                "norms": {
                  "enabled": false
                },
                "index_options": "docs",
                "analyzer": "sortable"
              },
              "whitespace": {
                "type": "string",
                "norms": {
                  "enabled": false
                },
                "fielddata": {
                  "format": "disabled"
                },
                "analyzer": "whitespace"
              }
            },
            "copy_to": [
              "search",
              "spelling",
              "autocomplete"
            ],
            "analyzer": "standard"
          }
        }
      }
    }
  }
}

{
  "magento2_default_catalog_product_20180124_102302": {
    "settings": {
      "index": {
        "creation_date": "1516789382129",
        "requests": {
          "cache": {
            "enable": "true"
          }
        },
        "number_of_replicas": "0",
        "translog": {
          "durability": "request",
          "disable_flush": "false"
        },
        "merge": {
          "scheduler": {
            "max_thread_count": "1"
          }
        },
        "uuid": "Pf9-vm2ZRqGoupq-KsUgtg",
        "analysis": {
          "char_filter": {
            "html_strip": {
              "type": "html_strip"
            }
          },
          "filter": {
            "phonetic": {
              "type": "phonetic",
              "encoder": "metaphone"
            },
            "word_delimiter": {
              "split_on_numerics": "1",
              "preserve_original": "1",
              "catenate_all": "1",
              "type": "word_delimiter",
              "catenate_words": "1",
              "catenate_numbers": "1",
              "split_on_case_change": "1",
              "generate_word_parts": "1"
            },
            "lowercase": {
              "type": "lowercase"
            },
            "pl_ascii_folding": {
              "type": "asciifolding",
              "preserve_original": "1"
            },
            "shingle": {
              "type": "shingle",
              "min_shingle_size": "2",
              "max_shingle_size": "2",
              "output_unigrams": "0"
            },
            "trim": {
              "type": "trim"
            },
            "ascii_folding": {
              "type": "asciifolding",
              "preserve_original": "0"
            }
          },
          "analyzer": {
            "whitespace": {
              "type": "custom",
              "char_filter": [
                "html_strip"
              ],
              "filter": [
                "word_delimiter",
                "lowercase",
                "ascii_folding",
                "trim"
              ],
              "tokenizer": "whitespace"
            },
            "shingle": {
              "type": "custom",
              "char_filter": [
                "html_strip"
              ],
              "filter": [
                "word_delimiter",
                "lowercase",
                "ascii_folding",
                "trim",
                "shingle"
              ],
              "tokenizer": "whitespace"
            },
            "phonetic": {
              "type": "custom",
              "char_filter": [
                "html_strip"
              ],
              "filter": [
                "word_delimiter",
                "lowercase",
                "ascii_folding",
                "trim",
                "phonetic"
              ],
              "tokenizer": "whitespace"
            },
            "standard": {
              "type": "custom",
              "char_filter": [
                "html_strip"
              ],
              "filter": [
                "word_delimiter",
                "lowercase",
                "ascii_folding",
                "trim"
              ],
              "tokenizer": "whitespace"
            },
            "sortable": {
              "type": "custom",
              "char_filter": [
                "html_strip"
              ],
              "filter": [
                "lowercase",
                "pl_ascii_folding",
                "trim"
              ],
              "tokenizer": "keyword"
            }
          }
        },
        "number_of_shards": "1",
        "refresh_interval": "1s",
        "version": {
          "created": "2040699"
        }
      }
    }
  }
}
4

whoever has any idea how to improve it?