mdmMarketSegment.getAncestorsAttribute();
Source mktSegmentAncestors = mdmMarketSegmentAncestorsAttr.getSource();
// Reverse the ancestors relation to get the descendants relation.
Source mktSegmentDescendants =
mktSegment.join(mktSegmentAncestors, mktSegment.value());
// Select an element of the hierarchy.
Source selVal = mktSegment.selectValue("MARKET_SEGMENT_AW::ACCOUNT_AW::23");
// Create a descendants relation that removes the input value.