config: Fix merge of config with map[string]string values.

Fixes #8679

config/compositeConfig.go

@@ -104,6 +104,10 @@ func (c *compositeConfig) Set(key string, value interface{}) {
 	c.layer.Set(key, value)
 }
 
+func (c *compositeConfig) SetDefaults(params maps.Params) {
+	c.layer.SetDefaults(params)
+}
+
 func (c *compositeConfig) WalkParams(walkFn func(params ...KeyParams) bool) {
 	panic("not supported")
 }

config/configProvider.go

@@ -30,6 +30,7 @@ type Provider interface {
 	Get(key string) interface{}
 	Set(key string, value interface{})
 	Merge(key string, value interface{})
+	SetDefaults(params maps.Params)
 	SetDefaultMergeStrategy()
 	WalkParams(walkFn func(params ...KeyParams) bool)
 	IsSet(key string) bool

config/defaultConfigProvider.go

@@ -163,10 +163,9 @@ func (c *defaultConfigProvider) Set(k string, v interface{}) {
 	}
 
 	switch vv := v.(type) {
-	case map[string]interface{}:
-		var p maps.Params = vv
+	case map[string]interface{}, map[interface{}]interface{}, map[string]string:
+		p := maps.MustToParamsAndPrepare(vv)
 		v = p
-		maps.PrepareParams(p)
 	}
 
 	key, m := c.getNestedKeyAndMap(k, true)
@@ -183,6 +182,16 @@ func (c *defaultConfigProvider) Set(k string, v interface{}) {
 	m[key] = v
 }
 
+// SetDefaults will set values from params if not already set.
+func (c *defaultConfigProvider) SetDefaults(params maps.Params) {
+	maps.PrepareParams(params)
+	for k, v := range params {
+		if _, found := c.root[k]; !found {
+			c.root[k] = v
+		}
+	}
+}
+
 func (c *defaultConfigProvider) Merge(k string, v interface{}) {
 	c.mu.Lock()
 	defer c.mu.Unlock()
@@ -226,10 +235,9 @@ func (c *defaultConfigProvider) Merge(k string, v interface{}) {
 	}
 
 	switch vv := v.(type) {
-	case map[string]interface{}:
-		var p maps.Params = vv
+	case map[string]interface{}, map[interface{}]interface{}, map[string]string:
+		p := maps.MustToParamsAndPrepare(vv)
 		v = p
-		maps.PrepareParams(p)
 	}
 
 	key, m := c.getNestedKeyAndMap(k, true)

config/defaultConfigProvider_test.go

@@ -204,6 +204,85 @@ func TestDefaultConfigProvider(t *testing.T) {
 		})
 	})
 
+	// Issue #8679
+	c.Run("Merge typed maps", func(c *qt.C) {
+
+		for _, left := range []interface{}{
+			map[string]string{
+				"c": "cv1",
+			},
+			map[string]interface{}{
+				"c": "cv1",
+			},
+			map[interface{}]interface{}{
+				"c": "cv1",
+			},
+		} {
+			cfg := New()
+
+			cfg.Set("", map[string]interface{}{
+				"b": left,
+			})
+
+			cfg.Merge("", maps.Params{
+				"b": maps.Params{
+					"c": "cv2",
+					"d": "dv2",
+				},
+			})
+
+			c.Assert(cfg.Get(""), qt.DeepEquals, maps.Params{
+				"b": maps.Params{
+					"c": "cv1",
+					"d": "dv2",
+				},
+			})
+		}
+
+		for _, left := range []interface{}{
+			map[string]string{
+				"b": "bv1",
+			},
+			map[string]interface{}{
+				"b": "bv1",
+			},
+			map[interface{}]interface{}{
+				"b": "bv1",
+			},
+		} {
+
+			for _, right := range []interface{}{
+				map[string]string{
+					"b": "bv2",
+					"c": "cv2",
+				},
+				map[string]interface{}{
+					"b": "bv2",
+					"c": "cv2",
+				},
+				map[interface{}]interface{}{
+					"b": "bv2",
+					"c": "cv2",
+				},
+			} {
+				cfg := New()
+
+				cfg.Set("a", left)
+
+				cfg.Merge("a", right)
+
+				c.Assert(cfg.Get(""), qt.DeepEquals, maps.Params{
+					"a": maps.Params{
+						"b": "bv1",
+						"c": "cv2",
+					},
+				})
+			}
+
+		}
+
+	})
+
 	c.Run("IsSet", func(c *qt.C) {
 		cfg := New()