[BUG] [REGRESSION] [JAVA] [SPRING] allOf no longer generating correct annotations in model getter method code for properties marked as Required and NotNull

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator?
• 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

When running the generator with a setup like

components:
  schemas:
    Mailbox:
      type: object
      allOf:
        - $ref: '#/components/schemas/MailboxProperties'
        - required:
          - name
          - userIdentifier
    MailboxProperties:
      type: object
      properties:
        name:
          type: string
          minLength: 1
          maxLength: 255
          nullable: false
        userIdentifier:
          type: string
          minLength: 1
          maxLength: 255
          nullable: false

the output in 7.13.0 and earlier looked like the following for the model of Mailbox for the name getter

  @NotNull @Size(min = 1, max = 255) 
  @Schema(name = "name", requiredMode = Schema.RequiredMode.REQUIRED)
  @JsonProperty("name")
  public String getName() {
    return name;
  }

with the upgrade to 7.14.0, this has lost the @NotNull annotation and has the incorrect value for the requiredMode

  @Size(min = 1, max = 255) 
  @Schema(name = "name", requiredMode = Schema.RequiredMode.NOT_REQUIRED)
  @JsonProperty("name")
  public @Nullable String getName() {
    return name;
  }

This is breaking alot of our services which rely on these to perform validation

openapi-generator version

I'm upgrading from 7.10.0 to 7.14.0 but verified the regression occurs in 7.14.0 as it doesnt occur with 7.13.0

OpenAPI declaration file content or url

openapi: 3.0.0
info:
  title: mailbox
  version: 1.0.0
paths:
  /mailboxes:
    post:
      requestBody:
        required: true
        content:
          application/json:
            schema:
              $ref: '#/components/schemas/Mailbox'
      responses:
        '201':
          description: created.
components:
  schemas:
    Mailbox:
      type: object
      allOf:
        - $ref: '#/components/schemas/MailboxProperties'
        - required:
          - name
          - userIdentifier
    MailboxProperties:
      type: object
      properties:
        name:
          type: string
          minLength: 1
          maxLength: 255
          nullable: false
        emailAddress:
          type: string
          format: email
          minLength: 1
          maxLength: 255
          nullable: false
        userIdentifier:
          type: string
          minLength: 1
          maxLength: 255
          nullable: false

Generation Details

Run via the gradle kotlin build.gradle.kts file the task openApiGenerate

plugins {
    id("java")
    id("org.openapi.generator") version "7.14.0"
}

group = "com.test"
version = "1.0-SNAPSHOT"

repositories {
    mavenCentral()
}

openApiGenerate {
    generatorName.set("spring")
    inputSpec.set("${projectDir}/openapi.yaml")
    outputDir.set("${buildDir}/generated/openapi")
    apiPackage.set("com.test.bob.api")
    modelPackage.set("com.test.bob.model")
    invokerPackage.set("com.test.bob.invoker")
    configOptions.set(
        mapOf(
            "configPackage" to "com.test.bob.configuration",
            "useSpringBoot3" to "true",
            "delegatePattern" to "true",
            "generatedConstructorWithRequiredArgs" to "false"
        )
    )
}
sourceSets["main"].java.srcDir("${buildDir}/generated/openapi/src/main/java")

Steps to reproduce

Generate the java code from the spec, inspect the model class for Mailbox, note the getter for name has been generated as

  @Size(min = 1, max = 255) 
  @Schema(name = "name", requiredMode = Schema.RequiredMode.NOT_REQUIRED)
  @JsonProperty("name")
  public @Nullable String getName() {
    return name;
  }

when this should be

  @NotNull @Size(min = 1, max = 255) 
  @Schema(name = "name", requiredMode = Schema.RequiredMode.REQUIRED)
  @JsonProperty("name")
  public String getName() {
    return name;
  }

Related issues/PRs

I think it maybe related to the fix for https://github.com/OpenAPITools/openapi-generator/pull/21342 in 7.1.4.0 version @wing328

Start by running the Gradle openApiGenerate task with the provided OpenAPI spec and Spring settings, comparing generated Mailbox getters between 7.13.0 and 7.14.0. Trace the Spring generator’s model-property annotation handling and use the shown name getter output as the acceptance check: required allOf properties should retain @NotNull, Required, and a non-null return type.