for i := range l.visitors {
		i := i
		g.Go(func() error {
			return l.visitors[i].Visit(fn)
		})
	}

	return g.Wait()
}

// EagerVisitorList implements Visit for the sub visitors it contains. All errors
// will be captured and returned at the end of iteration.
type EagerVisitorList []Visitor

// Visit implements Visitor, and gathers errors that occur during processing until
// all sub visitors have been visited.

            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") })

// Visitor is called with each object name, and returns true if visiting should continue
type Visitor func(name string) (shouldContinue bool)

func skipEmptyNames(visitor Visitor) Visitor {
	return func(name string) bool {
		if len(name) == 0 {
			// continue visiting
			return true
		}
		// delegate to visitor
		return visitor(name)
	}
}

        1 * visitor.visitInputFileProperty('inputFile', _, _, _, _, _, _, InputFilePropertyType.FILE)
        1 * visitor.visitInputFileProperty('inputFiles', _, _, _, _, _, _, InputFilePropertyType.FILES)
        1 * visitor.visitInputProperty('bean', { it.call().implementationClassIdentifier == NestedBean.name }, false)
        1 * visitor.visitInputProperty('bean.nestedInput', { it.call() == 'nested' }, false)

        if (expression.getType() == IncludeType.SYSTEM) {
            visitor.visitSystem(expression);
        } else if (expression.getType() == IncludeType.QUOTED) {
            visitor.visitQuoted(expression);
        } else if (expression.getType() == IncludeType.IDENTIFIER) {
            visitor.visitIdentifier(expression);

            builder.add(processValue(element, visitor));
        }
        return visitor.set(builder.build());
    }

    private <T> T processList(List<?> value, ValueVisitor<T> visitor) {
        if (value.isEmpty()) {
            return visitor.emptyList();
        }
        return visitor.list(processListElements(value, visitor));
    }

        public void visit(IdeDependencyVisitor visitor) {
            resolvePlusConfigurations(visitor);
            resolveMinusConfigurations(visitor);
            resolveAuxiliaryArtifacts(visitor);
            visitArtifacts(visitor);
            visitUnresolvedDependencies(visitor);
        }

        private void resolvePlusConfigurations(IdeDependencyVisitor visitor) {

    @Override
    public void walk(T root, V visitor) {
        Class<?> nodeType = resolveType(root);
        TypeMetadata typeMetadata = typeMetadataStore.getTypeMetadata(nodeType);
        visitor.visitRoot(typeMetadata, root);
        Map<T, String> nestedNodesOnPath = nestedNodeToQualifiedNameMapFactory.get();
        nestedNodesOnPath.put(root, "<root>");
        walkChildren(root, typeMetadata, null, visitor, nestedNodesOnPath);
    }

        def visitor = new TestInstanceMetadataVisitor()

        when:
        TypeMetadataWalker.instanceWalker(typeMetadataStore, TestNested.class).walk(myTask, visitor)

        then:
        visitor.roots == ["null::$myTask"] as List<String>
        visitor.nested == ["nested::null", "nestedList::null", "nestedListOfLists::null", "nestedMap::null", "nestedNamedList::null", "nestedProperty::null"] as List<String>