[BUG] maven plugin generating java classes with non standard annotations

[Cs4r]

Description

The current Java classes generated by the plugin exhibit a few notable issues:

1. Non-standard annotations such as @javax.annotation.Nonnull or @javax.annotation.Nullable from com.google.code.findbugs:jsr305:3.0.2 are utilised.

2. Annotations are placed at the method level instead of the recommended field level.

openapi-generator version

7.5.0

generatorName: java

OpenAPI declaration file content or url

{
  "openapi": "3.1.0",
  "info": {
    "title": "Sample contract",
    "version": "1.0.0"
  },
  "paths": {},
  "components": {
    "schemas": {
      "Request": {
        "type": "object",
        "required": ["token"],
        "properties": {
          "token": {
            "type": "string"
          }
        }
      }
    }
  }
}

Generation Details

Generated java class

/*
 * Sample contract
 * No description provided (generated by Openapi Generator https://github.com/openapitools/openapi-generator)
 *
 * The version of the OpenAPI document: 1.0.0
 * 
 *
 * NOTE: This class is auto generated by OpenAPI Generator (https://openapi-generator.tech).
 * https://openapi-generator.tech
 * Do not edit the class manually.
 */


package com.sample;

import java.net.URLEncoder;
import java.nio.charset.StandardCharsets;
import java.util.StringJoiner;
import java.util.Objects;
import java.util.Map;
import java.util.HashMap;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonTypeName;
import com.fasterxml.jackson.annotation.JsonValue;
import java.util.Arrays;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;


/**
 * Request
 */
@JsonPropertyOrder({
  Request.JSON_PROPERTY_TOKEN
})
@javax.annotation.Generated(value = "org.openapitools.codegen.languages.JavaClientCodegen", date = "2024-04-22T17:39:48.544568+02:00[Europe/Madrid]", comments = "Generator version: 7.5.0")
public class Request {
  public static final String JSON_PROPERTY_TOKEN = "token";
  private String token;

  public Request() { 
  }

  public Request token(String token) {
    this.token = token;
    return this;
  }

   /**
   * Get token
   * @return token
  **/
  @javax.annotation.Nonnull
  @JsonProperty(JSON_PROPERTY_TOKEN)
  @JsonInclude(value = JsonInclude.Include.ALWAYS)

  public String getToken() {
    return token;
  }


  @JsonProperty(JSON_PROPERTY_TOKEN)
  @JsonInclude(value = JsonInclude.Include.ALWAYS)
  public void setToken(String token) {
    this.token = token;
  }


  /**
   * Return true if this Request object is equal to o.
   */
  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o == null || getClass() != o.getClass()) {
      return false;
    }
    Request request = (Request) o;
    return Objects.equals(this.token, request.token);
  }

  @Override
  public int hashCode() {
    return Objects.hash(token);
  }

  @Override
  public String toString() {
    StringBuilder sb = new StringBuilder();
    sb.append("class Request {\n");
    sb.append("    token: ").append(toIndentedString(token)).append("\n");
    sb.append("}");
    return sb.toString();
  }

  /**
   * Convert the given object to string with each line indented by 4 spaces
   * (except the first line).
   */
  private String toIndentedString(Object o) {
    if (o == null) {
      return "null";
    }
    return o.toString().replace("\n", "\n    ");
  }

  /**
   * Convert the instance into URL query string.
   *
   * @return URL query string
   */
  public String toUrlQueryString() {
    return toUrlQueryString(null);
  }

  /**
   * Convert the instance into URL query string.
   *
   * @param prefix prefix of the query string
   * @return URL query string
   */
  public String toUrlQueryString(String prefix) {
    String suffix = "";
    String containerSuffix = "";
    String containerPrefix = "";
    if (prefix == null) {
      // style=form, explode=true, e.g. /pet?name=cat&type=manx
      prefix = "";
    } else {
      // deepObject style e.g. /pet?id[name]=cat&id[type]=manx
      prefix = prefix + "[";
      suffix = "]";
      containerSuffix = "]";
      containerPrefix = "[";
    }

    StringJoiner joiner = new StringJoiner("&");

    // add `token` to the URL query string
    if (getToken() != null) {
      joiner.add(String.format("%stoken%s=%s", prefix, suffix, URLEncoder.encode(String.valueOf(getToken()), StandardCharsets.UTF_8).replaceAll("\\+", "%20")));
    }

    return joiner.toString();
  }
}

Steps to reproduce

1. Use OpenApi spec provided
2. Generate java class (POJO)

Expected behaviour

To rectify these issues, the ideal Java class generation should adhere to the following specifications:

1. Use standard annotations like @javax.validation.constraints.NotNull
2. Place annotations at the field level.

The expected behaviour can be summarised as follows:

package com.sample;

import javax.annotation.processing.Generated;
import javax.validation.constraints.NotNull;
import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonPropertyOrder;


/**
 * Request
 * <p>
 * 
 * 
 */
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonPropertyOrder({
    "token"
})
public class Request {

    /**
     * 
     * (Required)
     * 
     */
    @JsonProperty("token")
    @NotNull
    private String token;

    /**
     * 
     * (Required)
     * 
     */
    @JsonProperty("token")
    public String getToken() {
        return token;
    }

    /**
     * 
     * (Required)
     * 
     */
    @JsonProperty("token")
    public void setToken(String token) {
        this.token = token;
    }

    public Request withToken(String token) {
        this.token = token;
        return this;
    }

    @Override
    public String toString() {
        StringBuilder sb = new StringBuilder();
        sb.append(Request.class.getName()).append('@').append(Integer.toHexString(System.identityHashCode(this))).append('[');
        sb.append("token");
        sb.append('=');
        sb.append(((this.token == null)?"<null>":this.token));
        sb.append(',');
        if (sb.charAt((sb.length()- 1)) == ',') {
            sb.setCharAt((sb.length()- 1), ']');
        } else {
            sb.append(']');
        }
        return sb.toString();
    }

    @Override
    public int hashCode() {
        int result = 1;
        result = ((result* 31)+((this.token == null)? 0 :this.token.hashCode()));
        return result;
    }

    @Override
    public boolean equals(Object other) {
        if (other == this) {
            return true;
        }
        if ((other instanceof Request) == false) {
            return false;
        }
        Request rhs = ((Request) other);
        return ((this.token == rhs.token)||((this.token!= null)&&this.token.equals(rhs.token)));
    }

}

This revised code adheres to the standard annotations and correctly places them at the field level, as requested.