if (map.containsKey(key)) {
      // When a collision happens, the colliding entry is the first entry
      // of the tail map.
      Entry<K, V> previousEntry = map.tailMap(key).entrySet().iterator().next();
      throw new IllegalArgumentException(
          "Duplicate keys in mappings "
              + previousEntry.getKey()
              + "="
              + previousEntry.getValue()
              + " and "
              + key

  /** Explicitly specifies the return type of this {@code Invokable}. */
  public final <R1 extends R> Invokable<T, R1> returning(TypeToken<R1> returnType) {
    if (!returnType.isSupertypeOf(getReturnType())) {
      throw new IllegalArgumentException(
          "Invokable is known to return " + getReturnType() + ", not " + returnType);
    }
    @SuppressWarnings("unchecked") // guarded by previous check

            return updateEntity(source, result);
        } catch (InstantiationException | IllegalAccessException e) {
            final String msg = "Cannot create a new instance: " + entityType.getName();
            throw new IllegalBehaviorStateException(msg, e);
        }
    }

    protected <RESULT extends BoostDocumentRule> RESULT updateEntity(Map<String, Object> source, RESULT result) {
        return result;
    }

            return updateEntity(source, result);
        } catch (InstantiationException | IllegalAccessException e) {
            final String msg = "Cannot create a new instance: " + entityType.getName();
            throw new IllegalBehaviorStateException(msg, e);
        }
    }

    protected <RESULT extends RelatedContent> RESULT updateEntity(Map<String, Object> source, RESULT result) {
        return result;
    }

  }

  private Object writeReplace() {
    return new SerializedForm<>(delegate());
  }

  private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  /** Serialized form of the map, to avoid serializing the constraint. */
  private static final class SerializedForm<B extends @Nullable Object> implements Serializable {

		ctx, cancel := context.WithTimeout(r.Context(), defaultContextTimeout)
		defer cancel()
		if _, err := globalEtcdClient.Get(ctx, "health"); err != nil {
			// etcd unreachable throw an error..
			switch r.Method {
			case http.MethodHead:
				apiErr := toAPIError(r.Context(), err)
				writeResponse(w, apiErr.HTTPStatusCode, nil, mimeNone)
			case http.MethodGet:

                    versionScheme.parseVersionConstraint(request.getArtifact().getVersion());
        } catch (InvalidVersionSpecificationException e) {
            result.addException(e);
            throw new VersionRangeResolutionException(result);
        }

        result.setVersionConstraint(versionConstraint);

        if (versionConstraint.getRange() == null) {

            return upgradedProperties.stream()
                .distinct()
                .collect(ImmutableList.toImmutableList());
        } catch (IOException e) {
            throw new UncheckedIOException(e);
        }
    }

    /**
     * Automatically accept changes that are valid property upgrades of a getter or setter.
     *
     * Here we automatically accept the following cases:

          urls.add(new URL("file", null, new File(entry).getAbsolutePath()));
        }
      } catch (MalformedURLException e) {
        throw new AssertionError("malformed class path entry: " + entry, e);
      }
    }
    return urls.build();
  }

  /**
   * These tests fail in JDK 9 and JDK 10 for an unknown reason. It might be the test; it might be

    final SetMultimap<K, V> unusableDelegate;

    static <K, V> PopulatableMapAsMultimap<K, V> create() {
      return new PopulatableMapAsMultimap<>();
    }

    @SuppressWarnings("unchecked") // all methods throw immediately
    PopulatableMapAsMultimap() {
      this.map = newHashMap();
      this.unusableDelegate =
          (SetMultimap<K, V>)
              newProxyInstance(