code: public static List<ComparisonExpression> extractSupportedSpatialComparisons(Expression filterExpression)
      {
          return extractConjuncts(filterExpression).stream()
                  .filter(ComparisonExpression.class::isInstance)
                  .map(ComparisonExpression.class::cast)
                  .filter(SpatialJoinUtils::isSupportedSpatialComparison)
                  .collect(toImmutableList());
      }
docs: Returns a subset of conjuncts matching one the following shapes:
  - ST_Distance(...) <= ...
  - ST_Distance(...) < ...
  - ... >= ST_Distance(...)
  - ... > ST_Distance(...)
  <p>
  Doesn't check or guarantee anything about ST_Distance functions arguments
  or the other side of the comparison.