code: protected StringBuilder startToString(String requestLabel) {
          StringBuilder stringBuilder = new StringBuilder(requestLabel);
          stringBuilder.append(" serviceVersion:").append(String.valueOf(_serviceVersion));
          stringBuilder.append(" xid:").append(String.valueOf(_xid));
          stringBuilder.append(" usePrivilegedPort:").append(String.valueOf(_usePrivilegedPort));
          return stringBuilder;
      }
docs: Start a StringBuilder for use in toString() (for logging).
  
  @param requestLabel
  @return the builder