code: public static Optional<Map<String, Pair<String, String>>> getColumnMapping(
              Map<String, Object> tableProperties)
      {
          requireNonNull(tableProperties);
  
          @SuppressWarnings("unchecked")
          String strMapping = (String) tableProperties.get(COLUMN_MAPPING);
          if (strMapping == null) {
              return Optional.empty();
          }
  
          // Parse out the column mapping
          // This is a comma-delimited list of "(presto, column:accumulo, fam:accumulo qualifier)" triplets
          ImmutableMap.Builder<String, Pair<String, String>> mapping = ImmutableMap.builder();
          for (String m : COMMA_SPLITTER.split(strMapping)) {
              String[] tokens = Iterables.toArray(COLON_SPLITTER.split(m), String.class);
              checkState(tokens.length == 3, format("Mapping of %s contains %d tokens instead of 3", m, tokens.length));
              mapping.put(tokens[0], Pair.of(tokens[1], tokens[2]));
          }
  
          return Optional.of(mapping.build());
      }
docs: Gets the value of the column_mapping property, or Optional.empty() if not set.
  <p>
  Parses the value into a map of Presto column name to a pair of strings, the Accumulo column family and qualifier.
  
  @param tableProperties The map of table properties
  @return The column mapping, presto name to (accumulo column family, qualifier)