* and will cause {@link #build} to fail.
     */
    @CanIgnoreReturnValue
    public <T extends B> Builder<B> put(Class<T> key, T value) {
      mapBuilder.put(key, value);
      return this;
    }

    /**
     * Associates all of {@code map's} keys and values in the built map. Duplicate keys are not

      }
    }

    /**
     * Scans the first {@code size} elements of {@code entries} looking for duplicate keys. If
     * duplicates are found, a new correctly-sized array is returned with the same elements (up to
     * {@code size}), except containing only the last occurrence of each duplicate key. Otherwise
     * {@code null} is returned.
     */
    private static <K, V> Entry<K, V> @Nullable [] lastEntryForEachKey(

                            problems,
                            Severity.WARNING,
                            "servers.server.id",
                            null,
                            "must be unique but found duplicate server with id " + server.getId());
                }
            }
        }

        List<Mirror> mirrors = settings.getMirrors();

        if (mirrors != null) {
            for (Mirror mirror : mirrors) {

            .suppressing(SetCreationTester.class.getMethods())
            // BiMap.entrySet() duplicate-handling behavior is too confusing for SetCreationTester
            .withSetUp(parentBuilder.getSetUp())
            .withTearDown(parentBuilder.getTearDown())
            .createTestSuite());
    /*
     * TODO(cpovirk): the Map tests duplicate most of this effort by using a

import org.gradle.api.tasks.InputFiles;
import org.gradle.api.tasks.Optional;
import org.gradle.api.tasks.OutputFile;
import org.gradle.api.tasks.TaskAction;

/**
 * Concatenates a list of files into one and removes duplicate lines.
 */
public class ConcatFilesTask extends DefaultTask {

    public ConcatFilesTask() {
        setDescription("Concat a list of files into one.");
    }

    /** List of files to concatenate */

type And struct {
	XMLName xml.Name `xml:"And" json:"And"`
	Prefix  string   `xml:"Prefix,omitempty" json:"Prefix,omitempty"`
	Tags    []Tag    `xml:"Tag,omitempty" json:"Tag,omitempty"`
}

var errDuplicateTagKey = Errorf("Duplicate Tag Keys are not allowed")

// isEmpty returns true if Tags field is null
func (a And) isEmpty() bool {
	return len(a.Tags) == 0 && a.Prefix == ""
}

// Validate - validates the And field

     * will throw an exception if there are duplicate key pairs. The {@code build()} method will
     * soon be deprecated.
     *
     * @throws IllegalArgumentException if duplicate key pairs were added
     */
    public ImmutableTable<R, C, V> build() {
      return buildOrThrow();
    }

    /**
     * Returns a newly-created immutable table, or throws an exception if duplicate key pairs were
     * added.
     *

        List<Element> duplicates = dependencies.stream()
                .filter(dependency -> {
                    String key = createDependencyKey(dependency);
                    if (seenDependencies.containsKey(key)) {
                        context.detail("Fixed: Removed duplicate dependency: " + key + " in " + sectionName);
                        return true; // This is a duplicate
                    } else {

     * and will cause {@link #build} to fail.
     */
    @CanIgnoreReturnValue
    public <T extends B> Builder<B> put(Class<T> key, T value) {
      mapBuilder.put(key, value);
      return this;
    }

    /**
     * Associates all of {@code map's} keys and values in the built map. Duplicate keys are not

     * will throw an exception if there are duplicate key pairs. The {@code build()} method will
     * soon be deprecated.
     *
     * @throws IllegalArgumentException if duplicate key pairs were added
     */
    public ImmutableTable<R, C, V> build() {
      return buildOrThrow();
    }

    /**
     * Returns a newly-created immutable table, or throws an exception if duplicate key pairs were
     * added.
     *