Support Clearing Help Text

Allow help text to be set to an empty string.  See
darccio/mergo#179.

go.mod

@@ -9,3 +9,5 @@ require (
 	github.com/spf13/cobra v0.0.6
 	golang.org/x/net v0.0.0-20200301022130-244492dfa37a
 )
+
+replace github.com/imdario/mergo => github.com/cwarden/mergo v0.3.12-0.20210528180603-9b708ca2c584

go.sum

@@ -15,6 +15,8 @@ github.com/coreos/go-systemd v0.0.0-20190321100706-95778dfbb74e/go.mod h1:F5haX7
 github.com/coreos/pkg v0.0.0-20180928190104-399ea9e2e55f/go.mod h1:E3G3o1h8I7cfcXa63jLwjI0eiQQMgzzUDFVpN/nH/eA=
 github.com/cpuguy83/go-md2man/v2 v2.0.0 h1:EoUDS0afbrsXAZ9YQ9jdu/mZ2sXgT1/2yyNng4PGlyM=
 github.com/cpuguy83/go-md2man/v2 v2.0.0/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
+github.com/cwarden/mergo v0.3.12-0.20210528180603-9b708ca2c584 h1:XSEGteLsF2wBKvdDLosPEl3WsUNgnheAmjtU5vQ8TV0=
+github.com/cwarden/mergo v0.3.12-0.20210528180603-9b708ca2c584/go.mod h1:EKrIwxq7vAFm5c42qpRoClmx16ahAuLuVnEXbXTobpE=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/dgrijalva/jwt-go v3.2.0+incompatible/go.mod h1:E3ru+11k8xSBh+hMPgOLZmtrrCbhqsmaPHjLKYnJCaQ=

objects/fields.go

@@ -45,7 +45,7 @@ func (o *CustomObject) UpdateField(fieldName string, updates Field) error {
 	for i, f := range o.Fields {
 		if f.FullName == fieldName {
 			found = true
-			if err := mergo.Merge(&updates, f); err != nil {
+			if err := mergo.Merge(&updates, f, mergo.WithNoOverrideEmptyStructValues); err != nil {
 				return errors.Wrap(err, "merging field updates")
 			}
 			o.Fields[i] = updates