Set<Principal> pr = this.getSubject().getPrincipals();
            for ( Iterator<Principal> ite = pr.iterator(); ite.hasNext(); ) {
                try {
                    KerberosPrincipal entry = (KerberosPrincipal) ite.next();
                    return entry.getRealm();
                }
                catch ( Exception e ) {
                    continue;

   * ParametricNullness parametric nullness}. If a type parameter instead ranges over only non-null
   * types (or if the type is a non-variable type, like {@code String}), then code should almost
   * never use this method, preferring instead to call {@code requireNonNull} so as to benefit from
   * its runtime check.
   *

 * instance of that type. In addition to implementing {@code Map}, the additional type-safe
 * operations {@link #putInstance} and {@link #getInstance} are available.
 *
 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
 * and a primitive type and its corresponding wrapper type may map to different values.
 *
 * <h3>Implementations</h3>
 *
 * <ul>

import java.io.InputStream;
import java.io.Reader;
import java.util.Map;

import org.apache.maven.artifact.repository.metadata.Metadata;

/**
 * Handles deserialization of metadata from some kind of textual format like XML.
 *
 */
public interface MetadataReader {

    /**
     * The key for the option to enable strict parsing. This option is of type {@link Boolean} and defaults to {@code

    Ordering<Object> objects = Ordering.explicit((Object) 1);
    Ordering<Number> numbers = Ordering.explicit((Number) 1);
    Ordering<Integer> integers = Ordering.explicit(1);

    // Like by like equals like
    Ordering<Number> a = numbers.compound(numbers);

    // The compound takes the more specific type of the two, regardless of order

    Ordering<Number> b = numbers.compound(objects);

    Ordering<Object> objects = Ordering.explicit((Object) 1);
    Ordering<Number> numbers = Ordering.explicit((Number) 1);
    Ordering<Integer> integers = Ordering.explicit(1);

    // Like by like equals like
    Ordering<Number> a = numbers.compound(numbers);

    // The compound takes the more specific type of the two, regardless of order

    Ordering<Number> b = numbers.compound(objects);

import javax.annotation.CheckForNull;

/**
 * An entry in a reference map.
 *
 * <p>Entries in the map can be in the following states:
 *
 * <p>Valid:
 *
 * <ul>
 *   <li>Live: valid key/value are set
 *   <li>Loading: loading is pending
 * </ul>
 *
 * <p>Invalid:
 *
 * <ul>
 *   <li>Expired: time expired (key/value may still be set)

 *
 * <p>Also, if caller suppresses unchecked warnings and passes in an {@code Iterable<String>} for
 * type {@code Iterable<Integer>}, the map won't be able to detect and throw type error.
 *
 * <p>Like any other {@code Map<Class, Object>}, this map may contain entries for primitive types,
 * and a primitive type and its corresponding wrapper type may map to different values.
 *

      }
    } else {
      /*
       * We'll call the user callback or collect the values only when all inputs complete,
       * regardless of whether some failed. This lets us avoid calling expensive methods like
       * Future.get() when we don't need to (specifically, for whenAllComplete().call*()), and it
       * lets all futures share the same listener.
       *

    void setValue(S segment, E entry, V value);
  }

  /**
   * An entry in a hash table of a {@link Segment}.
   *
   * <p>Entries in the map can be in the following states:
   *
   * <p>Valid: - Live: valid key/value are set
   *
   * <p>Invalid: - Collected: key/value was partially collected, but not yet cleaned up
   */
  interface InternalEntry<K, V, E extends InternalEntry<K, V, E>> {