throw new UnsupportedOperationException("Cannot get available versions in this test case");
            }

            @Override
            public ResolutionGroup retrieve(MetadataResolutionRequest request) {
                return retrieve(request.getArtifact(), request.getLocalRepository(), request.getRemoteRepositories());
            }

            @Override

        // Metadata cannot be found

        if (result.hasMetadataResolutionExceptions()) {
            throw result.getMetadataResolutionException(0);
        }

        // Metadata cannot be retrieved

        // Cyclic Dependency Error

        if (result.hasCircularDependencyExceptions()) {
            throw result.getCircularDependencyException(0);
        }

        // Version Range Violation

    }

    @GwtIncompatible @J2ktIncompatible private static final long serialVersionUID = 0;
  }

  /**
   * Returns a supplier which caches the instance retrieved during the first call to {@code get()}
   * and returns that value on subsequent calls to {@code get()}. See: <a
   * href="http://en.wikipedia.org/wiki/Memoization">memoization</a>
   *

    }
  }

  static void verifyThreadWasNotInterrupted() {
    assertFalse(Thread.currentThread().isInterrupted());
  }

  static void clearInterrupt() {
    Thread.interrupted();
  }

  /**
   * Retrieves the result of a {@code Future} known to be done but uses the {@code get(long,
   * TimeUnit)} overload in order to test that method.
   */
  static <V extends @Nullable Object> V getDoneFromTimeoutOverload(Future<V> future)

    Wagon getWagon(String protocol) throws UnsupportedProtocolException;

    @Deprecated
    Wagon getWagon(Repository repository) throws UnsupportedProtocolException, WagonConfigurationException;

    //
    // Retriever
    //
    void getArtifact(Artifact artifact, ArtifactRepository repository, TransferListener transferListener, boolean force)
            throws TransferFailedException, ResourceDoesNotExistException;

     *
     * @param key the key for which to retrieve the session data, must not be {@code null}
     * @return the session data associated with the key or {@code null} if none
     */
    @Nullable
    <T> T get(@Nonnull Key<T> key);

    /**
     * Retrieve of compute the data associated with the specified key.
     *
     * @param key the key for which to retrieve the session data, must not be {@code null}

    }
  }

  static void verifyThreadWasNotInterrupted() {
    assertFalse(Thread.currentThread().isInterrupted());
  }

  static void clearInterrupt() {
    Thread.interrupted();
  }

  /**
   * Retrieves the result of a {@code Future} known to be done but uses the {@code get(long,
   * TimeUnit)} overload in order to test that method.
   */
  static <V extends @Nullable Object> V getDoneFromTimeoutOverload(Future<V> future)

    OkHttpClient client = new OkHttpClient();

    // Create request for remote resource.
    Request request = new Request.Builder()
        .url(ENDPOINT)
        .build();

    // Execute the request and retrieve the response.
    try (Response response = client.newCall(request).execute()) {
      // Deserialize HTTP response to concrete type.
      ResponseBody body = response.body();

 *
 * @author Harry Heymann
 * @since 2.0
 */
@GwtCompatible
@FunctionalInterface
public interface Supplier<T extends @Nullable Object> extends java.util.function.Supplier<T> {
  /**
   * Retrieves an instance of the appropriate type. The returned object may or may not be a new
   * instance, depending on the implementation.
   *
   * @return an instance of the appropriate type
   */
  @Override

                }
            } catch (Exception e) {
                if (logger.isDebugEnabled()) {
                    logger.warn("Failed to retrieve plugin descriptor for {}: {}", plugin.getId(), e.getMessage(), e);
                } else {
                    logger.warn("Failed to retrieve plugin descriptor for {}: {}", plugin.getId(), e.getMessage());
                }
            }
        }

        return null;
    }