@Nullable
  private <T> T processSchema(String schema, SchemaProcessor<T> processor) {
    VirtualFile file = MavenSchemaProvider.getSchemaFile(schema);
    PsiFile psiFile = PsiManager.getInstance(myProject).findFile(file);
    if (!(psiFile instanceof XmlFile xmlFile)) return null;

    XmlDocument document = xmlFile.getDocument();
    XmlNSDescriptor desc = (XmlNSDescriptor)document.getMetaData();
    XmlElementDescriptor[] descriptors = desc.getRootElementsDescriptors(document);
    return doProcessSchema(descriptors, null, processor, new HashSet<>());
  }
@Nullable
  private <T> T processSchema(String schema, SchemaProcessor<T> processor)