Stream Variable ?
This wildcard is replaced with the value of a previously set, temporary variable. These temporary variables must be set within the stream and are only available while the stream is running.
Use of the wildcard
The wildcard is used in the following ways:
Variable name: test1
Variable value: hello
{stream.variable.?}
For the following input (?) --> test1
{stream.variable.test1}
The output is going to be --> hello
