Method keys

api/src/main/java/io/grpc/Metadata.java:323–334

Returns set of all keys in store. @return unmodifiable Set of keys

()

   * @return unmodifiable Set of keys
   */
  @SuppressWarnings("deprecation") // The String ctor is deprecated, but fast.
  public Set<String> keys() {
    if (isEmpty()) {
      return Collections.emptySet();
    }
    Set<String> ks = Sets.newHashSetWithExpectedSize(size);
    for (int i = 0; i < size; i++) {
      ks.add(new String(name(i), 0 /* hibyte */));
    }
    // immutable in case we decide to change the implementation later.
    return Collections.unmodifiableSet(ks);
  }

  /**
   * Adds the {@code key, value} pair. If {@code key} already has values, {@code value} is added to