[BUG][RUST|KOTLIN] Generated code does not compile: "AnyOfLessThanGreaterThan"

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
• Have you searched for related issues/PRs?
• What's the actual output vs expected output?
• [Optional] Sponsorship to speed up the bug fix or feature request (example)

Description

In my project, I cannot use the more recent versions of the openapi-generator (>=v7.5.0) because it produces code that does not compile.

openapi-generator version

reproducible on version 7.5.0, 7.6.0, 7.7.0

OpenAPI declaration file content or url

https://gist.github.com/bewee-i/27cb9af7c6a2c12756dd4a41d6fed124

Generation Details

java -jar ./openapi-generator-cli.jar generate -g rust -i api.yaml

java -jar ./openapi-generator-cli.jar generate -g kotlin -i api.yaml

Steps to reproduce

Execute code generation for the provided openapi description. The generated code does not compile because it contains the following:

src/models/profile_response.rs

#[derive(Clone, Default, Debug, PartialEq, Serialize, Deserialize)]
pub struct ProfileResponse {
    #[serde(rename = "email", default, with = "::serde_with::rust::double_option", skip_serializing_if = "Option::is_none")]
    pub email: Option<Option<Box<models::AnyOfLessThanGreaterThan>>>,
    #[serde(rename = "id", skip_serializing_if = "Option::is_none")]
    pub id: Option<String>,
}

src/main/kotlin/org/openapitools/client/models/ProfileResponse.kt

data class ProfileResponse (

    @Json(name = "email")
    val email: AnyOfLessThanGreaterThan? = null,

    @Json(name = "id")
    val id: kotlin.String? = null

) {


}

Start with the linked OpenAPI declaration and reproduce both commands for the Rust and Kotlin generators. Inspect src/models/profile_response.rs and src/main/kotlin/org/openapitools/client/models/ProfileResponse.kt, then verify the generated projects compile; done means neither output contains the reported invalid AnyOfLessThanGreaterThan usage.