modulecache

Maven dependency metadata de-duplication now happens as well when

serializing untransformed metadata.

Fixes #8311

This commit introduces the concept of "ecosystem", that can be

registered on an attributes schema. When a component is published,

it may provide a list of ecosystems. This list is used by consumers

when resolving. If, for some reason, variant resolution fails, and

that the consumer didn't use a plugin which provides the expected

ecosystem, the error message will indicate that they probably

miss a plugin that understands that ecosystem.

This is useful when a plugin extends an existing ecosystem with

additional attributes, that consumers may not be aware of. In

this case it is expected that the plugin declares an ecosystem.

Currently the error message will only indicate what ecosystem

is missing, and an optional description. It will not tell _how_

such plugin can be found, nor what plugins provide it.

By default, for adhoc components, publishing will use the

ecosystems of the producer. For example, for a Java project,

the published Gradle metadata file will include the java

ecosystem requirement.

For components which are not adhoc, they must implement the

`ComponentWithEcosystems` interface in order to tell which

ecosystems are in use.

This commit adds support for having requested capabilities

part of the module component selector, for external dependencies.

This means that if a component is using Gradle metadata, we can

read requested capabilities and honor them during selection.

This reworks where requested capabilities are stored, and in

particular moves them to the `ComponentSelector`, making them

properly part of the identity of a dependency. As such, two

dependencies requiring two different variants by using distinct

capabilities will now properly appear as two different dependencies

in the dependency graph, instead of two variants of the same

dependency.

Since the strategy for isolating caches changed, this is not

necessary anymore.

As `HashCode` was only overhead.

Introduce a hash of the component metadata rules, so that we can

cache different processed metadata based on the hash. This is a

performance optimization, which allows setting different processed

metadata on the "cached metadata" instance, based on a rules hash.

The rule hash is more stable when using class-based rules. If not,

then we have instance based rules which are opaque to Gradle, meaning

that we're going to create as many instances of processed metadata

as there are rules instantiated.