[Hearbteat]Set expected url format in case of parsing error (#37255)

URL mappings expect an object type, whereas heartbeat is setting it as a string in case of a parsing error. Fix that by appending url.full with the faulty url.

Author: emilioalvap

CHANGELOG.next.asciidoc

@@ -98,6 +98,7 @@ https://github.com/elastic/beats/compare/v8.8.1\...main[Check the HEAD diff]
 *Heartbeat*
 
 - Fix panics when parsing dereferencing invalid parsed url. {pull}34702[34702]
+- Fix mapping errors with invalid urls. {pull}37255[37255]
 
 *Metricbeat*
 

x-pack/heartbeat/monitors/browser/synthexec/synthtypes.go

@@ -95,6 +95,7 @@ func (se SynthEvent) ToMap() (m mapstr.M) {
 	if se.URL != "" {
 		u, e := url.Parse(se.URL)
 		if e != nil {
+			_, _ = m.Put("url", mapstr.M{"full": se.URL})
 			logp.L().Warn("Could not parse synthetics URL '%s': %s", se.URL, e.Error())
 		} else {
 			_, _ = m.Put("url", wraputil.URLFields(u))

x-pack/heartbeat/monitors/browser/synthexec/synthtypes_test.go

@@ -59,6 +59,31 @@ func TestToMap(t *testing.T) {
 				"truly_at_root": "v2",
 			},
 		},
+		{
+			"root fields with invalid URL",
+			mapstr.M{
+				"type":            JourneyStart,
+				"package_version": "1.2.3",
+				"root_fields": map[string]interface{}{
+					"synthetics": map[string]interface{}{
+						"nested": "v1",
+					},
+					"truly_at_root": "v2",
+				},
+				"url": "https://{example}.com",
+			},
+			mapstr.M{
+				"synthetics": mapstr.M{
+					"type":            JourneyStart,
+					"package_version": "1.2.3",
+					"nested":          "v1",
+				},
+				"url": mapstr.M{
+					"full": "https://{example}.com",
+				},
+				"truly_at_root": "v2",
+			},
+		},
 		{
 			"root fields, step metadata",
 			mapstr.M{