code: @Override
      public Buffer getBuffer() {
          // TODO: redo
          if (this.responseLine == null) {
              final StringBuilder sb = new StringBuilder();
              sb.append("SIP/2.0 ").append(this.statusCode).append(" ").append(this.reason.toString());
              this.responseLine = Buffers.wrap(sb.toString());
          }
  
          return this.responseLine;
      }
docs: {@inheritDoc}