code: synchronized final JsMsgPart getPayloadIfFluffed() {
          if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled()) {
              if (payload == null)
                  SibTr.debug(this, tc, "getPayloadIfFluffed returning null");
          }
          return payload;
      }
docs: Get the JsMsgPart which contains the JMF Message described by the
  schema for the data field in the JsPayload Schema, if it has already been
  fluffed up and cached.
  If the part is not already fluffed and cached, just return null as the caller
  does NOT want to fluff it up.
  
  @return JsMsgPart The message part for the JsPayload schema's data field, or null