* writer each time it is called.
   *
   * <p>The caller is responsible for ensuring that the returned writer is closed.
   *
   * @throws IOException if an I/O error occurs while opening the writer
   */
  public abstract Writer openStream() throws IOException;

  /**
   * Opens a new buffered {@link Writer} for writing to this sink. The returned stream is not

    @Test
    void testNoProblems() {
        ToolchainsBuildingException e = new ToolchainsBuildingException(Collections.<Problem>emptyList());
        assertEquals("0 problems were encountered while building the effective toolchains" + LS, e.getMessage());
    }

    @Test
    void testOneProblem() {
        ProblemCollector problemCollector = ProblemCollectorFactory.newInstance(null);

   * it does.
   *
   * @throws IOException if an I/O error occurs while reading from this source
   */
  public ImmutableList<String> readLines() throws IOException {
    Closer closer = Closer.create();
    try {
      BufferedReader reader = closer.register(openBufferedStream());
      List<String> result = Lists.newArrayList();
      String line;
      while ((line = reader.readLine()) != null) {
        result.add(line);

   * independent stream each time it is called.
   *
   * <p>The caller is responsible for ensuring that the returned stream is closed.
   *
   * @throws IOException if an I/O error occurs while opening the stream
   */
  public abstract OutputStream openStream() throws IOException;

  /**
   * Opens a new buffered {@link OutputStream} for writing to this sink. The returned stream is not

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    assertIntact(q);
    q.remove(9);
    q.remove(11);
    q.remove(10);
    // Now we're in the critical state: [1, 15, 13, 8, 14]
    // Removing 8 while iterating caused duplicates in iteration result.
    List<Integer> result = Lists.newArrayListWithCapacity(initial.size());
    for (Iterator<Integer> iter = q.iterator(); iter.hasNext(); ) {
      Integer value = iter.next();

  }

  boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
    Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));

        super("While configuring wagon for '" + repositoryId + "': " + message, cause);

        this.repositoryId = repositoryId;
        this.originalMessage = message;
    }

    public WagonConfigurationException(String repositoryId, String message) {
        super("While configuring wagon for '" + repositoryId + "': " + message);

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  }

  boolean removeEntriesIf(Predicate<? super Entry<K, Collection<V>>> predicate) {
    Iterator<Entry<K, Collection<V>>> entryIterator = unfiltered.asMap().entrySet().iterator();
    boolean changed = false;
    while (entryIterator.hasNext()) {
      Entry<K, Collection<V>> entry = entryIterator.next();
      K key = entry.getKey();
      Collection<V> collection = filterCollection(entry.getValue(), new ValuePredicate(key));