[BUG] validation is not applied when $ref is used

Bug Report Checklist

• Have you provided a full/minimal spec to reproduce the issue?
• What's the version of OpenAPI Generator used?
• What's the actual output vs expected output?

Description

when $ref is applied to model field, then validation properties is ignored

openapi-generator version

3.3.4

OpenAPI declaration file content or url

openapi: '3.0.0'
components:
  schemas:
    BaseUser:
      type: object
      properties:
        description:
          $ref: 'common-types.yaml#/components/schemas/ApplicableText'
          maxLength: 255

common-types.yaml

ApplicableText:
      type: string
      pattern: '^(?:\p{Alnum}|[ +@!#$%&''*-/=?^_`.{|}~]){1,}$'

Command line used for generation

mvn clean install

Steps to reproduce

copy-n-paste this example and generate dto

Actual output vs expected output

Actual:

public class BaseUserDto   {
  @JsonProperty("description")
  private String description;

  /**
   * Get description
   * @return description
  */
  @ApiModelProperty(value = "")
  @Pattern(regexp="^(?:\\p{Alnum}|[ +@!#$%&'*-/=?^_`.{|}~]){1,}$") 
  public String getDescription() {
    return description;
  }

  public void setDescription(String description) {
    this.description = description;
  }
..
}

Expected:
javax.validation.constraints.Size(max=255) to be present over getDescription()

Start with the minimal OpenAPI YAML declaration and the generated Java BaseUserDto shown in the report, then inspect how Java generation handles validation properties on fields using $ref. Run the reported mvn clean install workflow and confirm that the generated getter includes javax.validation.constraints.Size(max=255) alongside the existing pattern validation.