* @param source The source of the problem, may be {@code null}.
     * @param lineNumber The one-based index of the line containing the error or {@code -1} if unknown.
     * @param columnNumber The one-based index of the column containing the error or {@code -1} if unknown.
     * @param exception The exception that caused this problem, may be {@code null}.
     */
    // mkleint: does this need to be public?
    public DefaultModelProblem(

        assertTrue(
                message.contains("[ERROR] Missing required dependency @ pom.xml, line 25, column 10"),
                "Message should contain error details with location");

        assertTrue(
                message.contains("[ERROR] Invalid version format @ pom.xml, line 30, column 5"),
                "Message should contain second error details");

        assertTrue(

    //                                                                    ================
    // -----------------------------------------------------
    //                                       Column Property
    //                                       ---------------
    protected final Map<String, PropertyGateway> _epgMap = newHashMap();
    {

  @SuppressWarnings("Immutable") // We don't modify this after construction.
  private final int[] cellRowIndices;

  // For each cell in iteration order, the index of that cell's column key in the list of column
  // keys present in that row.
  @SuppressWarnings("Immutable") // We don't modify this after construction.
  private final int[] cellColumnInRowIndices;

  SparseImmutableTable(

     * @param lineNumber The one-based index of the line containing the problem or {@code -1} if unknown.
     * @param columnNumber The one-based index of the column containing the problem or {@code -1} if unknown.
     * @param exception The exception that caused this problem, may be {@code null}.
     */
    DefaultProblem(

    //                                                                    ================
    // -----------------------------------------------------
    //                                       Column Property
    //                                       ---------------
    protected final Map<String, PropertyGateway> _epgMap = newHashMap();
    {

    public Set<Cell<R, C, V>> cellSet() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.cellSet();
    }

    @Override
    public Map<R, V> column(C columnKey) {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.column(columnKey);
    }

    @Override
    public Set<C> columnKeySet() {
      assertTrue(Thread.holdsLock(mutex));
      return delegate.columnKeySet();
    }

    //                                                                    ================
    // -----------------------------------------------------
    //                                       Column Property
    //                                       ---------------
    protected final Map<String, PropertyGateway> _epgMap = newHashMap();
    {

    //                                                                    ================
    // -----------------------------------------------------
    //                                       Column Property
    //                                       ---------------
    protected final Map<String, PropertyGateway> _epgMap = newHashMap();
    {

    //                                                                    ================
    // -----------------------------------------------------
    //                                       Column Property
    //                                       ---------------
    protected final Map<String, PropertyGateway> _epgMap = newHashMap();
    {