code: public static void generateVertexLine(StringWriter sw, ObjectMapper mapper, VertexBean vBean) throws JsonGenerationException, JsonMappingException, IOException {
          sw.getBuffer().setLength(0);
          
          sw.append('V'); // Record type
          sw.append('=');
          
          mapper.writeValue(sw, vBean);
          
          sw.append('#');
          
          int hashCode = sw.toString().hashCode(); 
          sw.append(toHex(hashCode));
          sw.append('\n');
      }
docs: Efficient method to write a vertex -- avoids writeValueAsString