'existing' | 'existingValue'    | 'existingValue' | 'other'       | 'otherValue'       | 'otherValue'   | true
        'existing' | 'nonexistingValue' | 'existingValue' | 'other'       | 'otherValue'       | 'otherValue'   | false
        'existing' | 'nonexistingValue' | 'existingValue' | 'missing'     | 'missingValue'     | null           | false

        then:
        0 * onAccess._
        0 * onRemove._

        where:
        key        | removedValue    | reportedValue   | expectedResult
        'existing' | 'existingValue' | 'existingValue' | true
        'existing' | 'missingValue'  | 'existingValue' | false
        'missing'  | 'missingValue'  | null            | false

        // onRemove is only called if the value is actually removed

			return existingValue
		}
		for _, net := range networks {
			if net["name"] == istioCniNetwork {
				return existingValue
			}
		}
		return existingValue[0:i] + fmt.Sprintf(`, {"name": "%s"}`, istioCniNetwork) + existingValue[i:]
	}
	for _, net := range strings.Split(existingValue, ",") {
		if strings.TrimSpace(net) == istioCniNetwork {
			return existingValue
		}
	}

  }

  /** @throws IllegalArgumentException if {@code existingValue} is not null. */
  /*
   * We could have declared this method 'static' but the additional compile-time checks achieved by
   * referencing the type variables seem worthwhile.
   */
  final void checkNoDuplicate(R rowKey, C columnKey, @CheckForNull V existingValue, V newValue) {
    checkArgument(
        existingValue == null,

        N predecessor = incidentEdge.nodeU();

        Object existingValue = adjacentNodeValues.put(predecessor, PRED);
        if (existingValue != null) {
          adjacentNodeValues.put(predecessor, new PredAndSucc(existingValue));
        }

        orderedNodeConnectionsBuilder.add(new NodeConnection.Pred<>(predecessor));
        predecessorCount++;

  }

  /** @throws IllegalArgumentException if {@code existingValue} is not null. */
  /*
   * We could have declared this method 'static' but the additional compile-time checks achieved by
   * referencing the type variables seem worthwhile.
   */
  final void checkNoDuplicate(R rowKey, C columnKey, @CheckForNull V existingValue, V newValue) {
    checkArgument(
        existingValue == null,

        N predecessor = incidentEdge.nodeU();

        Object existingValue = adjacentNodeValues.put(predecessor, PRED);
        if (existingValue != null) {
          adjacentNodeValues.put(predecessor, new PredAndSucc(existingValue));
        }

        orderedNodeConnectionsBuilder.add(new NodeConnection.Pred<>(predecessor));
        predecessorCount++;

            if (readingObj instanceof List) {
                @SuppressWarnings("unchecked")
                final List<String> existingValues = (List<String>) readingObj;
                concatValues(existingValues, readings[i]);
                map.put(FieldNames.READING_PREFIX + i, existingValues.stream().distinct().toList());
            } else {

      int rowIndex = requireNonNull(rowKeyToIndex.get(rowKey));
      int columnIndex = requireNonNull(columnKeyToIndex.get(columnKey));
      V existingValue = values[rowIndex][columnIndex];
      checkNoDuplicate(rowKey, columnKey, existingValue, cell.getValue());
      values[rowIndex][columnIndex] = cell.getValue();
      rowCounts[rowIndex]++;
      columnCounts[columnIndex]++;
      cellRowIndices[i] = rowIndex;

      int rowIndex = requireNonNull(rowKeyToIndex.get(rowKey));
      int columnIndex = requireNonNull(columnKeyToIndex.get(columnKey));
      V existingValue = values[rowIndex][columnIndex];
      checkNoDuplicate(rowKey, columnKey, existingValue, cell.getValue());
      values[rowIndex][columnIndex] = cell.getValue();
      rowCounts[rowIndex]++;
      columnCounts[columnIndex]++;
      cellRowIndices[i] = rowIndex;