code: @NonNull public CMARichText addMarks(@NonNull CMARichMark... marks) {
      this.marks.addAll(Arrays.asList(marks));
      return this;
    }
docs: Adds the given marks to this texts marks.
  
  @param marks defines which marks to be added.
  @return this instance for chaining.
  @throws NullPointerException if marks is null.