XmlNode newChild = XmlNode.newInstance(child);
                List<XmlNode> newChildren = new ArrayList<>(xmlNode.children());
                newChildren.add(newChild);

                this.xmlNode = XmlNode.newBuilder()
                        .name(xmlNode.name())
                        .value(xmlNode.value())
                        .attributes(xmlNode.attributes())
                        .children(newChildren)
                        .namespaceUri(xmlNode.namespaceUri())
                        .prefix(xmlNode.prefix())
                        .inputLocation(xmlNode.inputLocation())
                        .build();
                clearCache();

                return new XmlPlexusConfiguration(newChild);
            } else {