}

    // add a follow-up plan to this one
    public void then(BuildPlan step) {
        step.plan.forEach((k, v) -> plan.merge(k, v, this::merge));
        aliases.putAll(step.aliases);
    }

    private Map<String, BuildStep> merge(Map<String, BuildStep> org, Map<String, BuildStep> add) {
        // all new phases should be added after the existing ones
        List<BuildStep> lasts =

  @Override
  public @Nullable V put(K key, V value) {
    return delegate.put(checkValid(key), value);
  }

  @Override
  public void putAll(Map<? extends K, ? extends V> map) {
    for (K key : map.keySet()) {
      checkValid(key);
    }
    delegate.putAll(map);
  }

  @Override
  public @Nullable V remove(Object key) {
    return delegate.remove(checkValid(key));
  }

  @Override

        HashMap<String, String> result = new HashMap<>(getSystemProperties());
        if (project != null) {
            result.putAll(project.getModel().getProperties());
        }
        result.putAll(getUserProperties());
        return result;
    }

    @Nonnull
    @Override
    public Version getMavenVersion() {

    /**
     * Copies all of the mappings from the specified map to this map.
     *
     * @param m the mappings to be stored in this map
     */
    @Override
    public void putAll(final Map<? extends String, ? extends Object> m) {
        parent.putAll(m);
    }

    /**
     * Removes all of the mappings from this map.
     */
    @Override
    public void clear() {
        parent.clear();
    }

            synchronized (
                    systemProperties) { // avoid concurrentmodification if someone else sets/removes an unrelated system
                // property
                this.systemProperties.putAll(systemProperties);
            }
        } else {
            this.systemProperties = null;
        }

        return this;
    }

    @Override
    public Properties getUserProperties() {

      assertTrue(Thread.holdsLock(mutex));
      return delegate.put(rowKey, columnKey, value);
    }

    @Override
    public void putAll(Table<? extends R, ? extends C, ? extends V> table) {
      assertTrue(Thread.holdsLock(mutex));
      delegate.putAll(table);
    }

    @Override
    public @Nullable V remove(Object rowKey, Object columnKey) {
      assertTrue(Thread.holdsLock(mutex));

     *
     * @throws NullPointerException if any key or value in {@code map} is null
     */
    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
      super.putAll(map);
      return this;
    }

    /**
     * Adds all of the given entries to the built bimap. Duplicate keys or values are not allowed,
     * and will cause {@link #build} to fail.

                    tmp.setProperty(key, entry.getValue());
                }
                envVars = tmp;
            }

            props.putAll(envVars);
        }
    }

      super.put(entry);
      return this;
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Map<? extends K, ? extends V> map) {
      return putAll(map.entrySet());
    }

    @CanIgnoreReturnValue
    @Override
    public Builder<K, V> putAll(Iterable<? extends Entry<? extends K, ? extends V>> entries) {
      for (Entry<? extends K, ? extends V> entry : entries) {
        put(entry);

  }

  public final void testPutAll() {
    for (Table<Character, Integer, String> testInstance : getTestInstances()) {
      assertThrows(
          UnsupportedOperationException.class,
          () -> testInstance.putAll(ImmutableTable.of('a', 1, "blah")));
    }
  }

  public final void testRemove() {
    for (Table<Character, Integer, String> testInstance : getTestInstances()) {