return new String(array);
  }

  /**
   * Returns the longest string {@code prefix} such that {@code a.toString().startsWith(prefix) &&
   * b.toString().startsWith(prefix)}, taking care not to split surrogate pairs. If {@code a} and
   * {@code b} have no common prefix, returns the empty string.
   *
   * @since 11.0
   */
  public static String commonPrefix(CharSequence a, CharSequence b) {

import java.util.List;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A simplistic set which implements the bare minimum so that it can be used in tests without
 * relying on any specific Set implementations. Slow. Explicitly allows null elements so that they
 * can be used in the testers.
 *
 * @author Regina O'Dell
 */

import java.util.List;
import java.util.Set;
import org.checkerframework.checker.nullness.qual.NonNull;
import org.checkerframework.checker.nullness.qual.Nullable;

/**
 * A simplistic set which implements the bare minimum so that it can be used in tests without
 * relying on any specific Set implementations. Slow. Explicitly allows null elements so that they
 * can be used in the testers.
 *
 * @author Regina O'Dell
 */

  }

  /**
   * Wraps around {@code TypeVariable<?>} to ensure that any two type variables are equal as long as
   * they are declared by the same {@link java.lang.reflect.GenericDeclaration} and have the same
   * name, even if their bounds differ.
   *
   * <p>While resolving a type variable from a {@code var -> type} map, we don't care whether the
   * type variable's bound has been partially resolved. As long as the type variable "identity"

    checkNotNull(reason);
    /*
     * All elements of `futures` are completed, or this future has already completed and read
     * `futures` into a local variable (in preparation for propagating cancellation to them). In
     * either case, no one needs to read `futures` for cancellation purposes later. (And
     * cancellation purposes are the main reason to access `futures`, as discussed in its docs.)
     */

   * Returns a hash table for the specified keys and values, and ensures that neither keys nor
   * values are null. This method may update {@code alternatingKeysAndValues} if there are duplicate
   * keys. If so, the return value will indicate how many entries are still valid, and will also
   * include a {@link Builder.DuplicateKey} in case duplicate keys are not allowed now or will not
   * be allowed on a later {@link Builder#buildOrThrow()} call.
   *

  private final double[] array;

  /*
   * TODO(kevinb): evaluate the trade-offs of going bimorphic to save these two fields from most
   * instances. Note that the instances that would get smaller are the right set to care about
   * optimizing, because the rest have the option of calling `trimmed`.
   */

  private final transient int start; // it happens that we only serialize instances where this is 0

   * Determines whether a character is a BMP digit according to <a
   * href="http://unicode.org/cldr/utility/list-unicodeset.jsp?a=%5Cp%7Bdigit%7D">Unicode</a>. If
   * you only care to match ASCII digits, you can use {@code inRange('0', '9')}.
   *
   * @deprecated Many digits are supplementary characters; see the class documentation.
   * @since 19.0 (since 1.0 as constant {@code DIGIT})
   */
  @Deprecated
  public static CharMatcher digit() {

   *       collections intelligently fall back to a binary search tree if hash table collisions are
   *       detected. Rather than going to all the trouble of reimplementing this ourselves, we
   *       simply switch over to use the JDK implementation wholesale if probable hash flooding is
   *       detected, sacrificing the compactness guarantee in very rare cases in exchange for much
   *       more reliable worst-case behavior.

  private final int[] array;

  /*
   * TODO(kevinb): evaluate the trade-offs of going bimorphic to save these two fields from most
   * instances. Note that the instances that would get smaller are the right set to care about
   * optimizing, because the rest have the option of calling `trimmed`.
   */

  private final transient int start; // it happens that we only serialize instances where this is 0