fix: patch additions honor source key style

When a patch appends a new node, it should honor the key style from the
patch. Prior to this commit, no style was applied, leading to problems
when the key value could be interpreted as a different type based on its
content. For example, "9110" needs quoting to ensure it is seen as a
string in yaml.

api/filters/patchstrategicmerge/patchstrategicmerge_test.go

@@ -776,6 +776,103 @@ spec:
       autoscaling: true
     deepgram-api:
       some: value
+`,
+		},
+
+		// Issue #4928
+		"support numeric keys": {
+			input: `
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "foobar"
+`,
+			patch: yaml.MustParse(`
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "barfoo"
+  "9110": "foo-foo"
+`),
+			expected: `
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "barfoo"
+  "9110": "foo-foo"
+`,
+		},
+
+		"honor different key style one": {
+			input: `
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  '6443': "foobar"
+`,
+			patch: yaml.MustParse(`
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "barfoo"
+  9110: "foo-foo"
+`),
+			expected: `
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  '6443': "barfoo"
+  9110: "foo-foo"
+`,
+		},
+
+		"honor different key style two": {
+			input: `
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "foobar"
+`,
+			patch: yaml.MustParse(`
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "barfoo"
+  '9110': "foo-foo"
+`),
+			expected: `
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: blabla
+  namespace: blabla-ns
+data:
+  "6443": "barfoo"
+  '9110': "foo-foo"
 `,
 		},
 	}