code: int estimateFieldValueSize(int accessor) {
      int size = 0;
      try {
        if (jmfPart.isPresent(accessor)) {
          size = jmfPart.estimateUnassembledValueSize(accessor);
        }
      }
      catch (JMFException e) {
        FFDCFilter.processException(e, "estimateFieldValueSize", "221", this);
        if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) SibTr.debug(this, tc, "estimateFieldValueSize failed: " + e);
      }
      return size;
    }
docs: Get the estimated size of the fluffed=up value of the field