if (isSelfLoop) {
      checkPositive(++selfLoopCount);
    }
    N previousNode = inEdgeMap.put(edge, node);
    checkState(previousNode == null);
  }

  @Override
  public void addOutEdge(E edge, N node) {
    checkNotNull(edge);
    checkNotNull(node);

    N previousNode = outEdgeMap.put(edge, node);
    checkState(previousNode == null);
  }

      Class<T> enumClass) {
    Map<String, WeakReference<? extends Enum<?>>> result = new HashMap<>();
    for (T enumInstance : EnumSet.allOf(enumClass)) {
      result.put(enumInstance.name(), new WeakReference<Enum<?>>(enumInstance));
    }
    enumConstantCache.put(enumClass, result);
    return result;
  }

  @GwtIncompatible // java.lang.ref.WeakReference

            if (metadata.getClass().getName().endsWith(".internal.VersionsMetadata")) {
                relatedMetadata.put(versionKey, (MergeableMetadata) metadata);
            }
            if (snapshotKey != null && metadata.getClass().getName().endsWith(".internal.RemoteSnapshotMetadata")) {
                relatedMetadata.put(snapshotKey, (MergeableMetadata) metadata);
            }
        }

            if (arMap.containsKey(accessResult.getUrl())) {
                throw new CrawlerSystemException(accessResult.getUrl() + " already exists.");
            }
            arMap.put(accessResult.getUrl(), accessResult);
        }

    }

    /*
     * (non-Javadoc)
     *
     * @see org.codelibs.fess.crawler.service.DataService#getCount(java.lang.String)
     */
    @Override

      assertCollectionIsUnmodifiable(multimap.get(key), sampleValue);
      assertMultimapRemainsUnmodified(multimap, originalEntries);
    }

    // Test #put()
    try {
      multimap.put(sampleKey, sampleValue);
      fail("put succeeded on unmodifiable multimap");
    } catch (UnsupportedOperationException expected) {
    }
    assertMultimapRemainsUnmodified(multimap, originalEntries);

      new ImmutableTable.Builder<String, SecretKey, HashFunction>()
          .put("HmacMD5", MD5_KEY, Hashing.hmacMd5(MD5_KEY))
          .put("HmacSHA1", SHA1_KEY, Hashing.hmacSha1(SHA1_KEY))
          .put("HmacSHA256", SHA256_KEY, Hashing.hmacSha256(SHA256_KEY))
          .put("HmacSHA512", SHA512_KEY, Hashing.hmacSha512(SHA512_KEY))
          .build();

  public void testNulls() {

            MapProperty<String, String> replacementTokens = task.getReplacementTokens();
            replacementTokens.put("version", moduleIdentity.getVersion().map(GradleVersion::getVersion));
            replacementTokens.put("baseVersion", moduleIdentity.getVersion().map(v -> v.getBaseVersion().getVersion()));

        for (int i = 1; key != null || value != null; i++) {
            List values = (List) map.get(key);
            if (values == null) {
                values = new ArrayList();
                map.put(key, values);
            }
            values.add(value);
            key = connection.getHeaderFieldKey(i);
            value = connection.getHeaderField(i);
        }

            return null;
        })).status(Status.OK).result());
    }

    // PUT /api/admin/fileauth/setting
    @Execute
    public JsonResponse<ApiResult> put$setting(final CreateBody body) {
        validateApi(body, messages -> {});
        if (!isValidFileConfigId(body.fileConfigId)) {

   */
  @CanIgnoreReturnValue
  private NetworkConnections<N, E> addNodeInternal(N node) {
    NetworkConnections<N, E> connections = newConnections();
    checkState(nodeConnections.put(node, connections) == null);
    return connections;
  }

  @Override
  @CanIgnoreReturnValue
  public boolean addEdge(N nodeU, N nodeV, E edge) {
    checkNotNull(nodeU, "nodeU");
    checkNotNull(nodeV, "nodeV");