Basic JMSMessageTransformer that uses the payload message of a JMS
TextMessage as the Chukwa record payload. If the message is not an instance
of TextMessage, or it is, but the payload is null or empty, returns null.
Parse any transformer-specific args to initialize the transformer. Return
a null if the arguments could not be parsed. This method will always be
invoked before transform is called only if transformer arguments were
passed. If they weren't, this method will never be called.