public SortedMap<C, V> subMap(C fromKey, C toKey) {
      checkArgument(rangeContains(checkNotNull(fromKey)) && rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, fromKey, toKey);
    }

    @Override
    public SortedMap<C, V> headMap(C toKey) {
      checkArgument(rangeContains(checkNotNull(toKey)));
      return new TreeRow(rowKey, lowerBound, toKey);
    }

    @Override

      }
    }

    @Override
    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
      synchronized (mutex) {
        return navigableMap(delegate().headMap(toKey, inclusive), mutex);
      }
    }

    @Override
    public SortedMap<K, V> headMap(K toKey) {
      return headMap(toKey, false);
    }

    @Override
    @CheckForNull

      }
    }

    @Override
    public NavigableMap<K, V> headMap(K toKey, boolean inclusive) {
      synchronized (mutex) {
        return navigableMap(delegate().headMap(toKey, inclusive), mutex);
      }
    }

    @Override
    public SortedMap<K, V> headMap(K toKey) {
      return headMap(toKey, false);
    }

    @Override
    @CheckForNull

    }

    @Override
    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey) {
      return headMap(toKey, false);
    }

    @Override
    public NavigableMap<K, Collection<V>> headMap(@ParametricNullness K toKey, boolean inclusive) {
      return new NavigableAsMap(sortedMap().headMap(toKey, inclusive));
    }

    @Override

    }

    @Override
    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
      return headMap(toKey, false);
    }

    @Override
    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
      return Maps.unmodifiableNavigableMap(delegate.headMap(toKey, inclusive));
    }

    @Override

    }

    @Override
    public SortedMap<K, V> headMap(@ParametricNullness K toKey) {
      return headMap(toKey, false);
    }

    @Override
    public NavigableMap<K, V> headMap(@ParametricNullness K toKey, boolean inclusive) {
      return Maps.unmodifiableNavigableMap(delegate.headMap(toKey, inclusive));
    }

    @Override

    /**
     * A key corresponding to the spec that is an immutable snapshot of the spec properties
     * suitable for usage in collections.
     */
    interface Key {}

    Key toKey();

    /**
     * A spec is considered configured when at least {@link #getLanguageVersion() language version} is set.
     * <p>
     * A spec that is not configured always directly matches the toolchain of the current JVM.

    public DefaultToolchainSpec() {
        getVendor().convention(getConventionVendor());
        getImplementation().convention(getConventionImplementation());
    }
    @Override
    public JavaToolchainSpecInternal.Key toKey() {
        return new Key(getLanguageVersion().getOrNull(), getVendor().getOrNull(), getImplementation().getOrNull());
    }

    @Override
    public boolean isConfigured() {

        return objectFactory.newInstance(SpecificInstallationToolchainSpec.class, JavaExecutableUtils.resolveJavaHomeOfExecutable(executable));
    }

    @Override
    public Key toKey() {
        return new Key(javaHome);
    }

    @Override
    public boolean isConfigured() {
        return true;
    }

    @Override
    public boolean isValid() {
        return true;
    }

							fromKey := from.Config().ClusterLocalFQDN()
							toKey := to.Config().ClusterLocalFQDN()
							if testTopology[fromKey] == nil {
								testTopology[fromKey] = map[string]int{}
							}
							testTopology[fromKey][toKey]++
						})
				},
				expect: map[string]map[string]int{
					"a.echo1.svc.cluster.local": {