code: public Set<String> getRemoveValues(String fieldName) {
          Utils.require(!Utils.isEmpty(fieldName), "fieldName");
          if (!m_valueRemoveMap.containsKey(fieldName)) {
              return null;
          }
          return new HashSet<>(m_valueRemoveMap.get(fieldName));
      }
docs: Get all values marked for removal for the given field. The result will be null
  if the given field has no values to remove. Otherwise, the set is copied.
  
  @param  fieldName    Name of link field.
  @return              Set of all values to be removed for the given link field, or
  null if there are none.