code: public static String getIdentifyingFieldName(int methodId, int continuationPointId) {
          if (continuationPointId < 0) {
              throw new IllegalArgumentException();
          }
  
          String methodIdStr = Integer.toString(methodId).replace('-', 'N');
          String continuationPointIdStr = Integer.toString(continuationPointId).replace('-', 'N');
          return "__COROUTINES_ID_" + methodIdStr + "_" + continuationPointIdStr;
      }
docs: Do not use -- for internal use only.
  <p>
  Get the name of the field that will be inserted into a class for some method id and version combination.
  @param methodId method id
  @param continuationPointId continuation point id
  @return field name
  @throws IllegalArgumentException if {@code continuationPointId < 0}