[BUG] Unable to create a pattern replace character filter without flags

[kmessaoudi]

What is the bug?

We are trying to create a index using this library and trying to create a pattern replace character filter with no flags. This is generating an error.

How can one reproduce the bug?

It works properly directly via the API.

PUT test-charfilter
{
  "settings": {
    "analysis": {
      
      "analyzer": {
        "analyzer_fr_FR": {
          "filter": [
            "lowercase",
            "asciifolding",
            "remove_duplicates"
          ],
          "type": "custom",
          "tokenizer": "standard",
          "char_filter": [
            "special_char_filter"
          ]
        }
      },
      "char_filter": {
        "special_char_filter": {
          "pattern": """["@\$#&*{}\[\],\.\=\+\-_\(\);'/\?"]""",
          "type": "pattern_replace",
          "replacement": ""
        }
      }
    }
  }
}

we will get

{
  "acknowledged": true,
  "shards_acknowledged": true,
  "index": "test-charfilter"
}

However, when using the lib :

// opensearchClient is injected through a bean
String templateSettings = "{"analysis":{"analyzer":{"analyzer_fr_FR":{"filter":["lowercase","asciifolding","remove_duplicates"],"type":"custom","tokenizer":"standard","char_filter":["special_char_filter"]}},"char_filter":{"special_char_filter":{"pattern":"""["@\$#&*{}\[\],\.\=\+\-_\(\);'/\?"]""","type":"pattern_replace","replacement":""}}}}";
JsonpMapper mapper = opensearchClient._transport().jsonpMapper();
JsonParser settingsParser =
      mapper
        .jsonProvider()
        .createParser(new StringReader(templateSettings));

IndexSettings indexSettings = IndexSettings._DESERIALIZER.deserialize(settingsParser, mapper);

return CreateIndexRequest.Builder()
      .settings(indexSettings)
      .build();

We will get this error

org.opensearch.client.util.MissingRequiredPropertyException - Missing required property 'PatternReplaceCharFilter.flags'

When checking the class opensearch PatternReplaceCharFilter flags is required

opensearch-java/java-client/src/main/java/org/opensearch/client/opensearch/_types/analysis/PatternReplaceCharFilter.java

Line 60 in 045c805

this.flags = ApiTypeHelper.requireNonNull(builder.flags, this, "flags");

However on the class elastic PatternReplaceCharFilter flags is not required

What is the expected behavior?

The expected behavior is to be able to build a PatternReplaceCharFilter with no flags or at least know what is the default value to use.

What is your host/environment?

Tested with

• a docker environment with opensearchproject/opensearch:2.11.1
• Library opensearch-java in version 2.9.0

Do you have any screenshots?

N/A

Do you have any additional context?

No