groovy

Report annotation choosen when multiple annotations exist

Add annotation metadata store

This is a first step towards better validation of property annotations.

Fix for previous commit on Windows.

Change class generation so that each type is validated once, rather than each time it appears in a type graph. Also report multiple validation problems, if they exist, rather than stopping on the first problem.

Fixes for previous commit.

Change `ClassInspector` so that it does not visit the entire type hierarchy for every type that is inspected, but instead reuses the results of visiting super types.

Handle new constant types in Java 12

Introduce a service that takes care of inspecting a type for properties, methods and other metadata. This is a step towards using a single mechanism to discover these things efficiently rather than doing so in a bunch of different ways and multiple times.

In this commit, refactor `ClassInspector` into this service and add some in-memory caching. This class was already used for class generation.

Use this service directly in `ConventionAwareHelper` and remove some ad hoc static caching. This avoids inspecting a type that has just been inspected for class generation when an instance is first created.

Also use this service in `OptionsReader`. While this wasn't a performance problem, this change means more consistent behaviour in how annotations are validated and work with Kotlin and Groovy classes (over time).