code: synchronized final JsMsgPart getPayload(JMFSchema schema) {
          if (payload == null) {
              if (TraceComponent.isAnyTracingEnabled() && tc.isDebugEnabled())
                  SibTr.debug(this, tc, "getPayload will call getPart");
              payload = jmo.getPayloadPart().getPart(JsPayloadAccess.PAYLOAD_DATA, schema);
          }
          return payload;
      }
docs: Get the JsMsgPart which contains the JMF Message described by the
  schema for the data field in the JsPayload Schema.
  Once obtained, the value is cached, and the cached value is returned until
  the cache is cleared.
  
  @param schema The schema to use to decode the data field of the JsPayload.
  
  @return JsMsgPart The message part for the JsPayload schema's data field