.installationToolchainsSource(
                        installationToolchainsFile != null && Files.exists(installationToolchainsFile)
                                ? Sources.fromPath(installationToolchainsFile)
                                : null)
                .userToolchainsSource(
                        userToolchainsPath != null && Files.exists(userToolchainsPath)

    @BeforeEach
    void setUp() throws Exception {
        policy = new DefaultGraphConflictResolutionPolicy();
        e1 = new MetadataGraphEdge("1.1", true, null, null, 2, 1);
        e2 = new MetadataGraphEdge("1.2", true, null, null, 3, 2);
        e3 = new MetadataGraphEdge("1.2", true, null, null, 2, 3);
    }

    // ------------------------------------------------------------------------------------------
    @Test

    }

    if (requestMethod != "GET") {
      // Don't cache non-GET responses. We're technically allowed to cache HEAD, QUERY and some
      // POST requests, but the complexity of doing so is high and the benefit is low.
      return null
    }

    if (response.hasVaryAll()) {
      return null
    }

    val entry = Entry(response)
    var editor: DiskLruCache.Editor? = null
    try {

    int initialSize = collection.size();
    assertTrue("remove(null) should return true", collection.remove(null));
    assertEquals(
        "remove(present) should decrease a collection's size by one.",
        initialSize - 1,
        collection.size());
    expectMissing((E) null);
  }

  @CollectionFeature.Require(absent = SUPPORTS_REMOVE)
  @CollectionSize.Require(absent = ZERO)

            getMap()
                .computeIfAbsent(
                    null,
                    k -> {
                      assertNull(k);
                      return v3();
                    }));
    expectUnchanged();
    expectNullKeyMissingWhenNullKeysUnsupported(
        "Should not contain null key after unsupported computeIfAbsent(null, function)");
  }

     * an empty string that by definition denotes the super POM.
     *
     * @return The model identifiers from the lineage of models, never {@code null}.
     */
    List<String> getModelIds();

    /**
     * Gets the assembled model.
     *
     * @return The assembled model, never {@code null}.
     */
    Model getEffectiveModel();

    /**

        if (includes != null) {
            includes = substVars(includes, INCLUDES_PROPERTY, configProps, callback);
            StringTokenizer st = new StringTokenizer(includes, "?\",", true);
            if (st.countTokens() > 0) {
                String location;
                do {
                    location = nextLocation(st);
                    if (location != null) {
                        boolean mandatory = true;

        this.servers = (servers != null) ? servers : new ArrayList<>();
        this.proxies = (proxies != null) ? proxies : new ArrayList<>();
        this.problems = (problems != null) ? problems : new ArrayList<>();
    }

    @Override
    public Server getServer() {
        return servers.isEmpty() ? null : servers.get(0);
    }

    @Override
    public List<Server> getServers() {

    Map<C, V> row = safeGet(rowMap(), rowKey);
    return row != null && Maps.safeContainsKey(row, columnKey);
  }

  @Override
  public @Nullable V get(@Nullable Object rowKey, @Nullable Object columnKey) {
    Map<C, V> row = safeGet(rowMap(), rowKey);
    return (row == null) ? null : safeGet(row, columnKey);
  }

  @Override
  public boolean isEmpty() {
    return size() == 0;
  }

     *
     * @param key the key under which to store the session data, must not be {@code null}
     * @param oldValue the expected data currently associated with the key, may be {@code null}
     * @param newValue the data to associate with the key, may be {@code null} to remove the mapping
     * @return {@code true} if the key mapping was successfully updated from the old value to the new value,