Revert "Replace wfMsgReplaceArgs by RawMessage"

This was merged too quickly, has several issues.

This reverts commit 6abefb274ff9cd86f75d5d13f713e1971e1b27ce.

Change-Id: Ibf3e464fa9eb534d599274dd9262a30d5a6a6948
Merge "Revert "Replace wfMsgReplaceArgs by RawMessage""