Use StableValue behind Lazy

[mp911de]

Update: JEP 502's successor is a draft for LazyConstants https://openjdk.org/jeps/8359894 with a much more aligned API.

We now use Java's StableValue to back our Lazy implementation. StableValue suggests an Optional orElse…(…) usage pattern and it is not primarily intended for lazifying value resolution, therefore we have to mimic StableValue.supplier(…).

An immediate benefit is that Java 25++ users will get concurrency guarding while our Lazy implementation uses a best effort non-locking approach for value resolution that may observe race conditions as we don't guarantee single Supplier access for the backing supplier object.

We're using Java's preview features through a multi-release jar keeping our Java 17 baseline but enabling Java 25 StableValue feature consumption. Using the 4.0.0-STABLE-VALUE-SNAPSHOT version requires enabling Java preview features during compilation and runtime.

<dependencies>
    <dependency>
        <groupId>org.springframework.data</groupId>
        <artifactId>spring-data-commons</artifactId>
        <version>4.0.0-STABLE-VALUE-SNAPSHOT</version>
    </dependency>
</dependencies>

<repositories>
    <repository>
        <id>spring-snapshot</id>
        <url>https://repo.spring.io/snapshot</url>
        <snapshots>
            <enabled>true</enabled>
        </snapshots>
    </repository>
</repositories>

[mp911de]

Will be superseded by LazyConstant.