Closes gh-18313

* pr/18445:
  Fix comment position in ZipHeaderPeekInputStreamTests

Closes gh-18445

See gh-18445

Closes gh-18414

Closes gh-18271

* pr/18378:
  Add Mustache to 'Customize ViewResolvers' docs section

Closes gh-18378

See gh-18378

See gh-18414

* pr/18339:
  Polish 'Apply TTL invocation caching on reactor types'
  Apply TTL invocation caching on reactor types

Closes gh-18339

Extract reactor specific code to an inner class to protect
against ClassNotFound exceptions if reactor is not in use.

Also add support for `Flux`.

See gh-18339

Update `CachingOperationInvoker` so that TTL caching is applied directly
to reactive types. Prior to this commit, a `Mono` would be cached, but
the values that it emitted would not.

See gh-18339

* pr/18333:
  Use ordered TaskExecutorCustomizers

Fixes gh-18333

Use an ordered stream in `TaskExecutionAutoConfiguration` when
obtaining the TaskExecutor customizers.

See gh-18333

Closes gh-18238

Closes gh-18407

Closes gh-18406

Closes gh-18405

Closes gh-18404

Closes gh-18403

Closes gh-18402

Closes gh-18401

Closes gh-18400

* pr/18347:
  Polish

Closes gh-18347

See gh-18347

* pr/18372:
  Fix typo in ApplicationContextAssert

Closes gh-18372

See gh-18372

Update `DataSourceInitializedPublisher` to fallback to the
`LocalContainerEntityManagerFactoryBean` if the
`javax.persistence.nonJtaDataSource` property is not defined.

As of Hibernate 4.3 the property is no longer set if the `EntityManager`
is created from a `PersistenceUnitInfo` instance rather than actual
properties.

Although this is being addressed in Hibernate issue HHH-13432, it's
not strictly a requirement of the JPA spec that the property is set.

Fixes gh-17061

See https://github.com/reactor/reactor-netty/issues/844

This also removes the need for the tomcat starter to be in provided
scope.

Closes gh-18346

Closes gh-18348

This will ensure that ReactiveManagementWebSecurityAutoConfiguration backs
off and that the actuator endpoints are also secured via OAuth2.

Fixes gh-17949

Fixes gh-18136

Previously, a number of usages of @ConditionalOnMissingBean prevented
a bean that implements an auto-configured bean's "main" interface from
causing the auto-configuration of the bean to back off. This would
happen when @ConditionalOnMissingBean did not specify a type, the
@Bean method returned the bean's concrete type, and that concreate
type implements a "main" interface.

This commit updates such usages of @ConditionalOnMissingBean to
specify the "main" interface as the type of the bean that must be
missing. This will allow, for example, the auto-configured
MongoTemplate bean to back off when a MongoOperations bean is defined.

Fixes gh-18101

Closes gh-18338

* pr/18331:
  Fix property name in "Task Execution and Scheduling" example

Closes gh-18331

See gh-18331

Closes gh-18319

See gh-18315