// has been changed.
	// +optional
	NestedValueValidation func(vv *NestedValueValidation) bool
}

// Visit recursively walks through the structural schema and calls the given callbacks
// at each node of those types.
func (m *Visitor) Visit(s *Structural) {
	m.visitStructural(s)
}

func (m *Visitor) visitStructural(s *Structural) bool {
	ret := false
	if m.Structural != nil {
		ret = m.Structural(s)
	}

            protected void visitChildren(Consumer<FileCollectionInternal> visitor) {
                visitor.accept(child1)
                visitor.accept(child2)
            }
        }
        def visitor = Mock(FileCollectionStructureVisitor)

        when:
        collection.visitStructure(visitor)

        then:
        1 * visitor.startVisit(FileCollectionInternal.OTHER, collection) >> true

        fileTree.visit(visitor)

        then:
        1 * visitor.visitDir({ it.file == tempDir.file("dir1") })
        1 * visitor.visitDir({ it.file == tempDir.file("dir2") })
        1 * visitor.visitDir({ it.file == tempDir.file("dir3") })
        1 * visitor.visitDir({ it.file == tempDir.file("dir2/dir1") })
        1 * visitor.visitDir({ it.file == tempDir.file("dir2/dir2") })

        when:
        visitor.stopOn = rootFile2
        fileTree.visit(visitor)

        then:
        visitor.visited == [rootFile1, rootFile2]

        when:
        visitor = new TestVisitor(true)
        visitor.stopOn = dirFile1
        fileTree.visit(visitor)

        then:
        visitor.visited == [rootFile1, rootFile2, dir1, dirFile1]

        where:

                visitFile(file, prefix + file.getName(), visitor);
            } else if (fileMetadata.getType() == FileType.Directory) {
                visitDir(file, prefix + file.getName() + "/", visitor);
            }
        }
    }

    private void visitFile(File file, String name, ClasspathEntryVisitor visitor) throws IOException {
        visitor.visit(new FileEntry(name, file));
    }

    private final List<DependencyGraphVisitor> visitors;

    public CompositeDependencyGraphVisitor(List<DependencyGraphVisitor> visitors) {
        this.visitors = visitors;
    }

    @Override
    public void start(RootGraphNode root) {
        for (DependencyGraphVisitor visitor : visitors) {
            visitor.start(root);
        }
    }

    @Override

    private final List<DependencyArtifactsVisitor> visitors;

    public CompositeDependencyArtifactsVisitor(List<DependencyArtifactsVisitor> visitors) {
        this.visitors = visitors;
    }

    @Override
    public void visitNode(DependencyGraphNode node) {
        for (DependencyArtifactsVisitor visitor : visitors) {
            visitor.visitNode(node);
        }
    }

    @Override

        then:
        1 * source1.visitStructure(_) >> { FileCollectionStructureVisitor visitor -> visitor.visitCollection(null, [dir1]) }
        1 * source2.visitStructure(_) >> { FileCollectionStructureVisitor visitor -> visitor.visitCollection(null, [dir2]) }
        1 * source3.visitStructure(_) >> { FileCollectionStructureVisitor visitor -> visitor.visitCollection(null, [dir3]) }
        0 * _
    }

        when:
        visitor.visitNode(rootNode)

        then:
        2 * rootNode.owner >> component
        1 * rootNode.root >> true
        1 * component.componentId >> identifier
        1 * component.metadataOrNull >> null

        and:
        visitor.allResolvedModules.empty
    }

    def 'finishes without error when visited match expected'() {
        given:

    def "visits message when unavailable"() {
        def visitor = Mock(DiagnosticsVisitor)

        given:
        def availability = new ToolChainAvailability()
        availability.unavailable("some reason")

        when:
        availability.explain(visitor)

        then:
        1 * visitor.node("some reason")
    }

    def "visits message when unsupported"() {