code: @NotNull
      @Contract("_ -> new")
      public static <T> Optional<T> of(@NotNull T value) {
          return new Optional<T>(value);
      }
docs: Returns an {@code Optional} with the specified present non-null value.
  
  @param <T> the type of value
  @param value  the value to be present, must be non-null
  @return an {@code Optional}
  @throws NullPointerException if value is null
  @see #ofNullable(java.lang.Object)