buildFile """
            task produce1(type: FileProducer) {
                output = file("out1.txt")
                content = "one"
            }
            task produce2(type: FileProducer) {
                output = file("out2.txt")
                content = "two"
            }
            def files = project.files(produce1, produce2)
            task merge(type: InputFilesTask) {

[[sub:producer-variants]]
== Producer variants

A producer may want to generate different artifacts for different kinds of consumers: for the same source code, different _binaries_ are produced.
Or, a project may produce artifacts which are for consumption by other projects (same repository) but not for external use.

    def "produces value and stores in backing cache later when not present"() {
        def producer = Mock(Function)
        def completion = Mock(Runnable)

        when:
        def result = cache.get("key", producer, completion)

        then:
        result == "value"

        and:
        1 * target.get("key") >> null
        1 * producer.apply("key") >> "value"
        1 * target.putLater("key", "value", completion)

          "url": "producer-1.0.jar",
          "size": 261,
          "sha1": "29acdaf26447e93ce0c8af7357e6fd4e2d1db71d",
          "md5": "6c53fdd588deb0abfc636c382e25d92e"
        }
      ]
    },
    {
      "name": "mongodbSupportApi",
      "attributes": {
        "org.gradle.usage": "java-api"
      },
      "files": [
        {
          "name": "producer-1.0.jar",

  <!-- that they should prefer consuming it instead. -->
  <!-- do-not-remove: published-with-gradle-metadata -->
  <modelVersion>4.0.0</modelVersion>
  <groupId>org.gradle.demo</groupId>
  <artifactId>producer</artifactId>
  <version>1.0</version>
  <dependencies>
    <dependency>
      <groupId>org.mongodb</groupId>
      <artifactId>mongodb-driver-sync</artifactId>
      <version>3.9.1</version>

        def clean = rootBuild.task('clean').dependsOn(cleanFoo).dependsOn(cleanBar)
        def generateFoo = foo.task('generateFoo').produces('build/foo', type)
        def generateBar = bar.task('generateBar').produces('build/bar', type).dependsOn(generateFoo)
        def generate = rootBuild.task('generate').dependsOn(generateBar).dependsOn(generateFoo)

        writeAllFiles()

        expect:

import ${org.gradle.api.artifacts.transform.TransformParameters.name}

allprojects {
    task producer(type: ${builder.producerTaskClassName}) {
        ${builder.producerConfig}
    }
    afterEvaluate {
        ${builder.producerConfigOverrides}
    }
    artifacts {
        implementation producer.output
    }

    task resolve(type: ShowFileCollection) {

        schema.attribute(attr2)
        producer.attribute(attr2)
        producer.attribute(attr3)

        expect:
        schema.withProducer(producer).selectionSchema.hasAttribute(attr1)
        schema.withProducer(producer).selectionSchema.hasAttribute(attr2)
        schema.withProducer(producer).selectionSchema.hasAttribute(attr3)
    }

                        + "This can lead to incorrect results being produced, depending on what order the tasks are executed",
                    consumer,
                    producer
                ))
                .solution("Declare task '" + producer + "' as an input of '" + consumer + "'")
                .solution("Declare an explicit dependency on '" + producer + "' from '" + consumer + "' using Task#dependsOn")

        """

        when:
        run(":producer", ":consumer")
        then:
        executed(":producer", ":consumer")

        when:
        run(":consumer", ":producer")
        then:
        executed(":producer", ":consumer")

        where:
        disabledTask << ["consumer", "producer"]
    }