With the introduction of `RuntimeHints`, we can now contribute
reflection, resources and proxies hints that describe the expected
runtime behavior of the application. While this can be verified at
runtime with smoke tests, managing such tests and compiling to native
there is not very efficient.
This commit introduces the new `RuntimeHintsAgent`, a Java agent that
instruments JDK methods related to `RuntimeHints`.
It is different from the GraalVM agent, which aims at collecting all the
required hints for the runtime behavior of an application and dump those
in the expected format.
Here, the `RuntimeHintsAgent` can collect the related invocations only
for a delimited scope (typically, a lambda within a test) and later
check those against a `RuntimeHints` instance. In the case of testing
`RuntimeHintsRegistrar` implementations, the process is reversed:
instead of manually checking for registered hints in a `RuntimeHints`
instance, tests should exercise the use cases and then check that the
recorded behavior is in line with the prepared hints.
This first commit adds the agent infrastructure that collects the
invocations for all relevant JDK methods.
See gh-27981
c86e678788