when:
        ClassDoc doc = withCategories {
            def doc = new ClassDoc('org.gradle.Class', content, document, classMetaData, extensionMetaData)
            builder.build(doc)
            doc.mergeContent()
        }

        then:
        doc.classExtensions.size() == 2

        doc.classExtensions[0].pluginId == 'a'
        doc.classExtensions[0].mixinClasses == [extensionA1, extensionA2] as Set

            commentBuilder.build(classDoc);
            propertiesBuilder.build(classDoc);
            methodsBuilder.build(classDoc);
            extensionsBuilder.build(classDoc);
            classDoc.mergeContent();
        } finally {
            listener.finish();
        }
    }

        memberRenderers.add(new MethodsRenderer(linkRenderer, listener));
        memberRenderers.add(new BlocksRenderer(linkRenderer, listener));
    }

    public void mergeContent(ClassDoc classDoc, Element parent) {
        listener.start(String.format("class %s", classDoc.getName()));
        try {
            Element chapter = parent.getOwnerDocument().createElement("chapter");

    List<ClassDoc> getSubClasses() {
        return subClasses
    }
    void addSubClass(ClassDoc subClass) {
        subClasses.add(subClass)
    }
    ClassDoc mergeContent() {
        classProperties.sort { it.name }
        classMethods.sort { it.metaData.overrideSignature }
        classBlocks.sort { it.name }
        classExtensions.sort { it.pluginId }
        return this
    }

				// in that case, try to lock again.
				break keepLock
			case ld.lockContext <- lkctx:
				// Send the lock context to anyone asking for it
			}
		}
	}
}

func mergeContext(ctx1, ctx2 context.Context) (context.Context, context.CancelFunc) {
	ctx, cancel := context.WithCancel(context.Background())
	go func() {
		select {
		case <-ctx1.Done():
		case <-ctx2.Done():