try (EvaluationContext.ScopeContext context = openScope()) {
            Value<? extends T> value = provider.calculateValue(consumer);
            if (value.isMissing()) {
                return value.asType();
            }
            return doMapValue(context, value).calculateValue(consumer);
        }
    }

    @Override
    public FileTree visit(Closure closure) {
        return visit(fileVisitorFrom(closure));
    }

    static FileVisitor fileVisitorFrom(Closure closure) {
        return DefaultGroovyMethods.asType(closure, FileVisitor.class);
    }

    @Override
    public FileTree visit(final Action<? super FileVisitDetails> visitor) {
        return visit(new FileVisitor() {
            @Override

        for (Provider<R> provider : items) {
            Value<? extends R> value = Providers.internal(provider).calculateValue(consumer);
            if (value.isMissing()) {
                return value.asType();
            }
            values.add(value);
        }

        ImmutableList.Builder<R> result = ImmutableList.builderWithExpectedSize(values.size());
        for (Value<? extends R> value : values) {

        }
    }

    @Nonnull
    protected Value<OUT> mapValue(EvaluationContext.ScopeContext context, Value<? extends IN> value) {
        if (value.isMissing()) {
            return value.asType();
        }
        return value.transform(transformer);
    }

    protected void beforeRead(EvaluationContext.ScopeContext context) {
        provider.getProducer().visitContentProducerTasks(producer -> {

        1 * source2.visit(visitor)
    }

    def visitsEachTreeWithClosure() {
        final Closure visitor = TestUtil.TEST_CLOSURE
        final FileVisitor closureAsVisitor = DefaultGroovyMethods.asType(visitor, FileVisitor.class)

        when:
        tree.visit(visitor)

        then:
        1 * source1.visit(closureAsVisitor)
        1 * source2.visit(closureAsVisitor)
    }

      "diskURI": "diskURIValue",
      "cachingMode": "cachingModeValue",
      "fsType": "fsTypeValue",
      "readOnly": true,
      "kind": "kindValue"
    },
    "photonPersistentDisk": {
      "pdID": "pdIDValue",
      "fsType": "fsTypeValue"
    },
    "portworxVolume": {
      "volumeID": "volumeIDValue",
      "fsType": "fsTypeValue",
      "readOnly": true
    },
    "scaleIO": {

  photonPersistentDisk:
    fsType: fsTypeValue
    pdID: pdIDValue
  portworxVolume:
    fsType: fsTypeValue
    readOnly: true
    volumeID: volumeIDValue
  quobyte:
    group: groupValue
    readOnly: true
    registry: registryValue
    tenant: tenantValue
    user: userValue
    volume: volumeValue
  rbd:
    fsType: fsTypeValue
    image: imageValue

          "cachingMode": "cachingModeValue",
          "fsType": "fsTypeValue",
          "readOnly": true,
          "kind": "kindValue"
        },
        "photonPersistentDisk": {
          "pdID": "pdIDValue",
          "fsType": "fsTypeValue"
        },
        "portworxVolume": {
          "volumeID": "volumeIDValue",
          "fsType": "fsTypeValue",
          "readOnly": true
        },

    inlineVolumeSpec:
      accessModes:
      - accessModesValue
      awsElasticBlockStore:
        fsType: fsTypeValue
        partition: 3
        readOnly: true
        volumeID: volumeIDValue
      azureDisk:
        cachingMode: cachingModeValue
        diskName: diskNameValue
        diskURI: diskURIValue
        fsType: fsTypeValue
        kind: kindValue
        readOnly: true
      azureFile:
        readOnly: true

          "cachingMode": "cachingModeValue",
          "fsType": "fsTypeValue",
          "readOnly": true,
          "kind": "kindValue"
        },
        "photonPersistentDisk": {
          "pdID": "pdIDValue",
          "fsType": "fsTypeValue"
        },
        "portworxVolume": {
          "volumeID": "volumeIDValue",
          "fsType": "fsTypeValue",
          "readOnly": true
        },