Document on how to add the jspecify dependency: Maven and Gradle

[sdavids]

Please add a section to the README similar to the one at @API Guardian.

You might also want to add it to either Start Here and/or Nullness User Guide.

Maven

<dependency>
  <groupId>org.jspecify</groupId>
  <artifactId>jspecify</artifactId>
  <version>0.3.0</version>
</dependency>

or

<dependency>
  <groupId>org.jspecify</groupId>
  <artifactId>jspecify</artifactId>
  <version>0.3.0</version>
  <scope>provided</scope>
</dependency>

Related: #389

Gradle

The Java Library plugin configurations

dependencies {
  api("org.jspecify:jspecify:0.3.0")
}

or

dependencies {
  implementation("org.jspecify:jspecify:0.3.0")
}

or

dependencies {
  compileOnlyApi("org.jspecify:jspecify:0.3.0")
}

or

dependencies {
  compileOnly("org.jspecify:jspecify:0.3.0")
}

If it is not compileOnlyApi you might want to add a link to an appropriate FAQ entry.

[tbroyer]

Fwiw, because JSpecify can be used at runtime, I'd favor api in Gradle (and not-provided, not-optional in Maven). Those who don't use the annotations at runtime, and don't want to ship the JSpecify JAR in their application can safely exclude it from their deliverables, but the rule should be that it's "included by default".
(it is an anti-pattern to mark annotation dependencies as compileOnly or compileOnlyApi, it depends on the annotation retention: source → compileOnly, class → compileOnlyApi, runtime → api; in Maven: source → provided/optional is the closest you can do, class or runtime → compile)

[GregDThomas]

I'd favor api in Gradle

For libraries, yes. For applications, I would think compileOnly would be fine, no?

[tbroyer]

If you're using the java (or application) plugin in Gradle, rather than java-library, for an application, then you don't have api and compileOnlyApi, and you only have to choose between implementation and compileOnly, which is what I hinted above: if you don't use the annotations at runtime, and don't want to ship the JSpecify JAR in your application, you can safely use compileOnly, otherwise use implementation.