code: private boolean skipCommaSpaces2() throws IOException {
          wsp1: for (;;) {
              switch (current) {
                  default:
                      break wsp1;
                  case 0x20:
                  case 0x9:
                  case 0xD:
                  case 0xA:
                      break;
              }
              current = reader.read();
              appendToContext(current);
          }
  
          if (current != ',')
              return false; // no comma.
  
          wsp2: for (;;) {
              switch (current = reader.read()) {
                  default:
                      appendToContext(current);
                      break wsp2;
                  case 0x20:
                  case 0x9:
                  case 0xD:
                  case 0xA:
                      appendToContext(current);
                      break;
              }
          }
          return true; // had comma
      }
docs: Skips the whitespaces and an optional comma.
  
  @returns true if comma was skipped.