Spring Boot's testing support registers a DynamicPropertyRegistry as a
bean in the ApplicationContext, which conflicts with the
DynamicPropertyRegistry registered as a bean by the Spring TestContext
Framework (TCF) since Spring Framework 6.2 M2.
To avoid that conflict and to improve the user experience for Spring's
testing support, this commit introduces a DynamicPropertyRegistrar API
to replace the DynamicPropertyRegistry bean support.
Specifically, the TCF no longer registers a DynamicPropertyRegistry as
a bean in the ApplicationContext.
Instead, users can now register custom implementations of
DynamicPropertyRegistrar as beans in the ApplicationContext, and the
DynamicPropertiesContextCustomizer now registers a
DynamicPropertyRegistrarBeanInitializer which eagerly initializes
DynamicPropertyRegistrar beans and invokes their accept() methods with
an appropriate DynamicPropertyRegistry.
In addition, a singleton DynamicValuesPropertySource is created and
registered with the Environment for use in
DynamicPropertiesContextCustomizer and
DynamicPropertyRegistrarBeanInitializer, which allows
@DynamicPropertySource methods and DynamicPropertyRegistrar beans to
transparently populate the same DynamicValuesPropertySource.
Closes gh-33501
e7b52cf8b2