If you input is a list, did you try loop over and then pass through. As per the BIS, A document containing these three keys:
Key Value
cx_timeout 1000
cx_max 2500
cx_min 10
Would be converted to a document list containing these three documents:
pName cx_timeout
pValue 1000
pName cx_max
pValue 2500
pName cx_min
pValue 10
#Flow-and-Java-services#Integration-Server-and-ESB#webMethods