[BUG] DerivedField contains additional unsupported `name` parameter

[e-wag]

What is the bug?

When building a DerivedField using the OpenSearch Java client, the generated mapping
includes a name field within the derived field definition (also see here). This causes OpenSearch to
return a mapper_parsing_exception error: "unknown parameter [name] on mapper
[derivedField] of type [date]".

How can one reproduce the bug?

1. Use the OpenSearch Java client to create a DerivedField.
2. The client generates a mapping like the following JSON as one is forced to provide name as a field:

{
    "derived": {
      "derivedFieldName": {
        "format": "yyyy-MM-dd",
        "name": "derivedFieldName", // Problematic name parameter
        "script": { ... },
        "type": "date"
      }
    }
}

3. Submit this mapping to OpenSearch.

What is the expected behavior?

The mapping should be accepted by OpenSearch without errors. The name` field should not be present, as it is not supported according to these docs here.

What is your host/environment?

• OpenSearch Java client 3.5.0
• OpenSearch server 3.5.0
• macOS 26.3.1

Do you have any additional context?

As far as I can tell, the name should be the key of the map in the search request here.

[andrross]

Catch All Triage - 1 2

[gingeekrishna]

Opened PR #2036 with the fix.

Root cause: _common___DerivedField in the OpenAPI spec included name as a required property, so the generated DerivedField.java serialized it unconditionally. In the derived fields API, the field name is the map key in the parent object — it must not appear inside the field definition.

Fix: Removed name from the spec schema (both properties and required) and updated the generated file accordingly — 33 lines deleted, no other changes.