implement POST message creation

vendor/github.com/google/uuid/README.md

@@ -0,0 +1,21 @@
+# uuid
+The uuid package generates and inspects UUIDs based on
+[RFC 4122](https://datatracker.ietf.org/doc/html/rfc4122)
+and DCE 1.1: Authentication and Security Services. 
+
+This package is based on the github.com/pborman/uuid package (previously named
+code.google.com/p/go-uuid).  It differs from these earlier packages in that
+a UUID is a 16 byte array rather than a byte slice.  One loss due to this
+change is the ability to represent an invalid UUID (vs a NIL UUID).
+
+###### Install
+```sh
+go get github.com/google/uuid
+```
+
+###### Documentation 
+[![Go Reference](https://pkg.go.dev/badge/github.com/google/uuid.svg)](https://pkg.go.dev/github.com/google/uuid)
+
+Full `go doc` style documentation for the package can be viewed online without
+installing this package by using the GoDoc site here: 
+http://pkg.go.dev/github.com/google/uuid