Class Key

api/src/main/java/io/grpc/NameResolver.java:714–738

Identifies an externally-defined custom argument that can be stored in Args. Uses reference equality so keys should be defined as global constants. @param type of values that can be stored under this key

     * @param <T> type of values that can be stored under this key
     */
    @Immutable
    @SuppressWarnings("UnusedTypeParameter")
    public static final class Key<T> {
      private final String debugString;

      private Key(String debugString) {
        this.debugString = debugString;
      }

      @Override
      public String toString() {
        return debugString;
      }

      /**
       * Creates a new instance of {@link Key}.
       *
       * @param debugString a string used to describe the key, used for debugging.
       * @param <T> Key type
       * @return a new instance of Key
       */
      public static <T> Key<T> create(String debugString) {
        return new Key<>(debugString);
      }
    }
  }

  /**