public static @Nullable SchemaPrefix resolvePrefix(PsiElement element, String name) {
    XmlExtension extension = XmlExtension.getExtension(element.getContainingFile());
    return extension.getPrefixDeclaration(PsiTreeUtil.getParentOfType(element, XmlTag.class, false), name);
  }
public static @Nullable SchemaPrefix resolvePrefix(PsiElement element, String name)