merged spec caused null pointer exception

[minesunny]

Description

merged spec caused null pointer exception

openapi-generator version

7.4.0

OpenAPI declaration file content or url

servers:
- url: "http://localhost:8080"
openapi: "3.0.3"
paths:
  /dict:
    $ref: "./Dict.yaml#/paths/~1dict"
  /dataSource:
    $ref: "./DataSource.yaml#/paths/~1dataSource"
  /dict/page:
    $ref: "./Dict.yaml#/paths/~1dict~1page"
  /driver:
    $ref: "./Driver.yaml#/paths/~1driver"
  /dataSource/page:
    $ref: "./DataSource.yaml#/paths/~1dataSource~1page"
  /dataSourceTree:
    $ref: "./DataSourceTree.yaml#/paths/~1dataSourceTree"
  /dataSourceTree/menu:
    $ref: "./DataSourceTree.yaml#/paths/~1dataSourceTree~1menu"
info:
  title: "merged spec"
  description: "merged spec"
  version: "1.0.0"

Command line used for generation

openapi-generator-cli generate --input-spec-root-directory ./api/
-g spring -o generated-spring-boot-openapi \

Steps to reproduce

Related issues/PRs

Suggest a fix/enhancement

mered spec file doesn't have body content