docs: public static List<FunctionCall> extractSupportedSpatialFunctions(Expression filterExpression)
      {
          return extractConjuncts(filterExpression).stream()
                  .filter(FunctionCall.class::isInstance)
                  .map(FunctionCall.class::cast)
                  .filter(SpatialJoinUtils::isSupportedSpatialFunction)
                  .collect(toImmutableList());
      }