@Nullable
  public XmlAttribute getAttribute(String qname) {
    if (qname == null) return null;
    final XmlAttribute[] attributes = getAttributes();

    final boolean caseSensitive = isCaseSensitive();

    for (final XmlAttribute attribute : attributes) {
      final LeafElement attrNameElement =
          (LeafElement) XmlChildRole.ATTRIBUTE_NAME_FINDER.findChild(attribute.getNode());
      if (attrNameElement != null
          && (caseSensitive && Comparing.equal(attrNameElement.getChars(), qname)
              || !caseSensitive && Comparing.equal(attrNameElement.getChars(), qname, false))) {
        return attribute;
      }
    }
    return null;
  }
  public XmlAttribute setAttribute(String qname, String value) throws IncorrectOperationException {
    final XmlAttribute attribute = getAttribute(qname);

    if (attribute != null) {
      if (value == null) {
        deleteChildInternal(attribute.getNode());
        return null;
      }
      attribute.setValue(value);
      return attribute;
    } else if (value == null) {
      return null;
    } else {
      PsiElement xmlAttribute =
          add(XmlElementFactory.getInstance(getProject()).createXmlAttribute(qname, value));
      while (!(xmlAttribute instanceof XmlAttribute)) xmlAttribute = xmlAttribute.getNextSibling();
      return (XmlAttribute) xmlAttribute;
    }
  }