Update openapi-generator-online Dockerfile to use openjdk11 image

[wing328]

Update openapi-generator-online Dockerfile to use openjdk11 image

PR checklist

• Read the contribution guidelines.
• Pull Request title clearly describes the work in the pull request and Pull Request description provides details about how to validate the work. Missing information here may result in delayed response from the community.
• Run the following to build the project and update samples:

  ./mvnw clean package 
  ./bin/generate-samples.sh
  ./bin/utils/export_docs_generators.sh
  

  Commit all changed files.
  This is important, as CI jobs will verify all generator outputs of your HEAD commit as it would merge with master.
  These must match the expectations made by your contribution.
  You may regenerate an individual generator by passing the relevant config(s) as an argument to the script, for example ./bin/generate-samples.sh bin/configs/java*.
  For Windows users, please run the script in Git BASH.
• In case you are adding a new generator, run the following additional script :

  ./bin/utils/ensure-up-to-date
  

  Commit all changed files.
• File the PR against the correct branch: master (6.3.0) (minor release - breaking changes with fallbacks), 7.0.x (breaking changes without fallbacks)
• If your PR is targeting a particular programming language, @mention the technical committee members, so they are more likely to review the pull request.

[wing328]

tested locally:

docker build modules/openapi-generator-online/ -t test3

[+] Building 3.0s (9/9) FINISHED                                                                                                                                                                                                            
 => [internal] load build definition from Dockerfile                                                                                                                                                                                   0.0s
 => => transferring dockerfile: 562B                                                                                                                                                                                                   0.0s
 => [internal] load .dockerignore                                                                                                                                                                                                      0.0s
 => => transferring context: 2B                                                                                                                                                                                                        0.0s
 => [internal] load metadata for docker.io/adoptopenjdk/openjdk11:alpine-jre                                                                                                                                                           2.8s
 => [auth] adoptopenjdk/openjdk11:pull token for registry-1.docker.io                                                                                                                                                                  0.0s
 => [1/3] FROM docker.io/adoptopenjdk/openjdk11:alpine-jre@sha256:bae359898bcbc5ef0fd7949477ab8c2e3542f508176700f54662fe3d4bf66d3b                                                                                                     0.0s
 => [internal] load build context                                                                                                                                                                                                      0.0s
 => => transferring context: 85B                                                                                                                                                                                                       0.0s
 => CACHED [2/3] WORKDIR /generator                                                                                                                                                                                                    0.0s
 => CACHED [3/3] COPY target/openapi-generator-online.jar /generator/openapi-generator-online.jar                                                                                                                                      0.0s
 => exporting to image                                                                                                                                                                                                                 0.0s
 => => exporting layers                                                                                                                                                                                                                0.0s
 => => writing image sha256:c9686af3b9ffef01628a65087d85224d0caea777382059a6a65b6e994be7883c                                                                                                                                           0.0s
 => => naming to docker.io/library/test3                                                                                                                                                                                               0.0s
➜  openapi-generator7 git:(online-docker) docker run test3                                       
SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/generator/openapi-generator-online.jar!/BOOT-INF/lib/logback-classic-1.2.11.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/generator/openapi-generator-online.jar!/BOOT-INF/lib/slf4j-simple-1.7.36.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::               (v2.5.14)

2023-06-29 07:26:12.153  INFO 1 --- [           main] o.o.codegen.online.OpenAPI2SpringBoot    : Starting OpenAPI2SpringBoot v7.0.0-SNAPSHOT using Java 11.0.19 on 35d53df9c258 with PID 1 (/generator/openapi-generator-online.jar started by root in /generator)
2023-06-29 07:26:12.161  INFO 1 --- [           main] o.o.codegen.online.OpenAPI2SpringBoot    : No active profile set, falling back to 1 default profile: "default"
2023-06-29 07:26:16.132  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2023-06-29 07:26:16.163  INFO 1 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2023-06-29 07:26:16.167  INFO 1 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet engine: [Apache Tomcat/9.0.63]
2023-06-29 07:26:16.427  INFO 1 --- [           main] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2023-06-29 07:26:16.427  INFO 1 --- [           main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 4101 ms
2023-06-29 07:26:20.782  INFO 1 --- [           main] o.s.b.a.w.s.WelcomePageHandlerMapping    : Adding welcome page: class path resource [static/index.html]
2023-06-29 07:26:20.970  WARN 1 --- [           main] o.s.b.a.m.MustacheAutoConfiguration      : Cannot find template location: classpath:/templates/ (please add some templates, check your Mustache configuration, or set spring.mustache.check-template-location=false)
2023-06-29 07:26:21.215  INFO 1 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2023-06-29 07:26:22.286  INFO 1 --- [           main] o.o.codegen.online.OpenAPI2SpringBoot    : Started OpenAPI2SpringBoot in 11.706 seconds (JVM running for 13.985)