docs: private static @Nullable String getContractFromAnnotation(Symbol.MethodSymbol sym) {
      for (AnnotationMirror annotation : sym.getAnnotationMirrors()) {
        Element element = annotation.getAnnotationType().asElement();
        assert element.getKind().equals(ElementKind.ANNOTATION_TYPE);
        if (((TypeElement) element)
            .getQualifiedName()
            .contentEquals("org.jetbrains.annotations.Contract")) {
          for (Map.Entry<? extends ExecutableElement, ? extends AnnotationValue> e :
              annotation.getElementValues().entrySet()) {
            if (e.getKey().getSimpleName().contentEquals("value")) {
              String value = e.getValue().toString();
              if (value.startsWith("\"") && value.endsWith("\"")) {
                value = value.substring(1, value.length() - 1);
              }
              return value;
            }
          }
        }
      }
      return null;
    }