See gh-805

* pr/805:
  Upgrade to Maven 3.8.2

Closes gh-805

Fixes #91

In 2021 we really should be using the browser's own date picker.

The current docker-compose.yml is still in version 1, which is
deprecated: https://docs.docker.com/compose/compose-file/compose-versioning/

So if you try to run `docker-compose up` with a recent version of
docker-compose, the following error occurs:
    (root) Additional property mysql is not allowed

Version 2.2 was chosen because it's not deprecated, but it also has been
released some time ago: Compose version 2.2 requires docker engine
version 1.13.0, which was released on 2017-01-18. So, with this version,
hopefully no users will have any issues either with deprecation warnings
or with a version that is not yet supported by their docker-engine.

See #636

Owner is really the aggregate root in DDD terms and there is no
need to directly access the Pet entity.

Rely on Hibernate to do lazy loading on visits.

The postgres user needs to be an owner of the public schema or a
superuser in order to execute the schema.sql for database
initialization.

To avoid that, two changes are required:
 - use `CREATE TABLE IF NOT EXISTS` in order to idempotently create the
   necessary tables
 - handle conflicts when inserting duplicate data

This follows the pattern in use by the
src/main/resources/db/mysql/{data,schema.sql} files.

Authored-by: Shaan Sapra <shsapra@vmware.com>

This is reverting a workaround for a Hibernate "feature". There's
no need for the child entities (Pet and Visit) to know about their
parent (foreign key). Hibernate can manage that just fine with a
@joincolumn. But it needs a nullable foreign key column in the
DB schema. That's the downside. The upside is much less code in
Java.

Introduced Owner.addVisit(…) to avoid that state transition to live in controller code.

Slightly polished some assertions in ClinicServiceTests.

Remove Java 8

Open session in view was switched off accidentally a while ago. Also
the mapping changes recently meant that the changes to @Valid model
attributes were not being propagated correctly.

Fixes #946 and #947

Fixes #936

Also works in codespaces.

Add Spring Boot extensions

@pivotal-cla This is an Obvious Fix
This fixes a compilation error in PetClinicIntegrationTests
Upgrade to same version as used in pom.xml

* Use stream instead of forEach on find PetType logic of parse()

* Improve controllers readability

* Rollback stream instead of for-each

In order to improve efficiency (see spring-projects/spring-framework#27619)
and allow native image compatibility, this commit uses WebJars versioned URLs
which are supported out of the box on Spring Boot via /META-INF/resources
default resource location configuration, removing the need to use
webjars-locator-core dependency and WebJarsResourceResolver.

I have been able to measure a consistent 5% startup time improvement on
the JVM with that simple change on my local machine.

Make sure we use the suggested fragment inclusion syntax. Use th:insert instead of th:include. Use simpler URI path segment templating to avoid duplication of expressions.

Avoid trailing slashes in URIs creates as upcoming Spring Boot versions will not map the trailing slash flavors of defined URI mappings.

Needed for JAXB annotations in the sources on Java 17.

 - Switch to Caffeine for caching since it is supported on native unlike Ehcache
 - Use latest metadata repository 0.2.3 (will be the default with Native Build Tools 0.9.15)
 - Registers resource hints for WebJars and db resource directory

Fixes #1151