code: private void compileColumns() {
          log.debug("Compiling columns string: " + getColumns());
          String[] chunks = JMeterPluginsUtils.replaceRNT(getColumns()).split("\\|");
          log.debug("Chunks " + chunks.length);
          compiledFields = new int[chunks.length];
          compiledVars = new int[chunks.length];
          compiledConsts = new ByteBuffer[chunks.length];
          for (int n = 0; n < chunks.length; n++) {
              int fieldID = availableFieldNames.indexOf(chunks[n]);
              if (fieldID >= 0) {
                  //log.debug(chunks[n] + " field id: " + fieldID);
                  compiledFields[n] = fieldID;
              } else {
                  compiledFields[n] = -1;
                  compiledVars[n] = -1;
                  if (chunks[n].contains(VAR_PREFIX)) {
                      log.debug(chunks[n] + " is sample variable");
                      String varN = chunks[n].substring(VAR_PREFIX.length());
                      try {
                          compiledVars[n] = Integer.parseInt(varN);
                      } catch (NumberFormatException e) {
                          log.error("Seems it is not variable spec: " + chunks[n]);
                          compiledConsts[n] = ByteBuffer.wrap(chunks[n].getBytes());
                      }
                  } else {
                      log.debug(chunks[n] + " is const");
                      if (chunks[n].length() == 0) {
                          //log.debug("Empty const, treated as |");
                          chunks[n] = "|";
                      }
  
                      compiledConsts[n] = ByteBuffer.wrap(chunks[n].getBytes());
                  }
              }
          }
      }
docs: making this once to be efficient and avoid manipulating strings in switch
  operators