code: @Override
      protected void initInputSource(WstxInputSource newInput, boolean isExt, String entityId)
          throws XMLStreamException
      {
          if (mFlattenWriter != null) {
              // Anything to flush from previous buffer contents?
              mFlattenWriter.flush(mInputBuffer, mInputPtr);
              mFlattenWriter.disableOutput();
              try {
                  /* Then let's let base class do the 'real' input source setup;
                   * this includes skipping of optional XML declaration that we
                   * do NOT want to output
                   */
                  super.initInputSource(newInput, isExt, entityId);
              } finally {
                  // This will effectively skip declaration
                  mFlattenWriter.enableOutput(mInputPtr);
              }
          } else {
              super.initInputSource(newInput, isExt, entityId);
          }
      }
docs: /*
  /////////////////////////////////////////////////////////
  Overridden input handling
  /////////////////////////////////////////////////////////